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Systematics of the New World Species of Marsilea (Marsileaceae)Author(s): David M. JohnsonSource: Systematic Botany Monographs, Vol. 11, Systematics of the New World Species ofMarsilea (Marsileaceae) (Jun. 25, 1986), pp. 1-87Published by: American Society of Plant TaxonomistsStable URL: http://www.jstor.org/stable/25027626 .

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SYSTEMATICS OF THE NEW WORLD SPECIES OF MARSILEA

(MARSILEACEAE)

David M. Johnson

Division of Biological Sciences and Herbarium

University of Michigan Ann Arbor, Michigan 48109

Abstract. A systematic revision of the New World species of Marsilea (Marsileaceae), involv

ing field, greenhouse, herbarium, and laboratory studies, was conducted. Comparison of Marsileaceae

to floating-leaved rhizomatous aquatic angiosperms revealed numerous structural convergences be

tween the two, and suggested that adaptation to flotation was an important factor in determining the

morphology of the Marsilea leaf. The plants showed extreme environmental plasticity. Stomatal pat terns and presence of epidermal streaks on the leaflets, which had been used systematically, were

shown to be variable. Other vegetative characters, such as position of roots on the rhizome, were

relatively stable. Vessel elements with simple perforation plates were found in roots of all species

except M. deflexa and M. crotophora, which had only tracheids with oblique scalariform end walls.

The life-history of Marsilea shares characteristics with those of many weedy angiosperms, including

long propagule dormancies, l ^-compatibility, occurrence in early successional habitats, and rapid

growth. Waterbirds seem to be important in sporocarp dispersal of species of Marsilea. The fossil

record shows that the Marsileaceae orginiated before or during the Lower Cretaceous, and extant

genera were present possibly by the Upper Cretaceous. The fossil genus Rodeites is similar to extant

species of Marsilea. Twelve species, including the newly described M. crotophora, and three putative

hybrids are recognized among the New World marsileas. To focus future taxonomic work in Marsilea

on natural rather than geographically defined groups, these taxa have been placed into three sections, two of which, section Clemys and section Nodorhizae, are newly described. Each species is illustrated

and its range mapped.

INTRODUCTION

The aquatic fern family Marsileaceae, which includes the water-clovers or

pepperworts (Marsilea), the pillworts (Pilularia Linnaeus), and the monotypic

Regnellidium Lindman, has long been a focus of interest for plant morphologists and physiologists. Members of this family have attracted attention for their un

fernlike attributes, including nocturnal leaf movements (Darwin 1880), hetero

phylly (Hildebrand 1870), production of latex in Regnellidium (Labouriau 1952),

presence of vessel elements (White 1961; Bhardwaja & Baijal 1977), and produc tion of sporangia inside sclerified seedlike propagules, the sporocarps. Members

of these three genera continue to be used as research subjects in plant cytology and morphogenesis.

Marsilea, a genus of approximately 45 species, was monographed by Alex

ander Braun in 1871. Braun studied the genus for over 30 years; he had not only herbarium specimens at his disposal but also cultivated a dozen species and per formed environmental manipulations upon them. His classification was adopted

substantially intact in later synopses of the genus by Baker (1886), Sadebeck

(1902), and Gupta (1962); these authors added new species but did not fundamen

tally reorganize Braun's classification scheme.

1



2 MARSILEA IN THE NEW WORLD VOLUME 11

It has been clear for some time, however, that Braun's criteria for distinguish

ing among species, based upon a limited number of specimens, do not allow

satisfactory identification of many collections that have been made since his time.

Correll (1956) recognized that "Marsilea is sorely in need of careful modern

revision." Morton (1969) remarked that "Braun's work on Marsilea has never

really been reviewed or checked, a task that urgently needs doing." Such remarks were the result not only of study of specimens that represented new taxa or that

blurred the distinctions between recognized taxa, but also of failure of most

pteridologists, unused to dealing with phenotypically plastic aquatic plants, to

allow for this in Marsilea taxonomy.

By the time of Morton's observation concerning Braun's work, however, the

matter had already been addressed to some degree by revision of the Indian

species of Marsilea by Gupta (1962) and of the African and Madagascan species

by Launert (1968). Species of the New World had yet to be treated in similar

fashion, the most recent revision being the synopsis of Underwood and Cook

(1887). A conspectus of New World marsileas could only be obtained by consult

ing numerous floristic works (Mickel 1979 for North America; Knobloch & Cor

rell 1962 for Chihuahua, Mexico; Stolze 1983 for Guatemala; Vareschi 1969 for

Venezuela; Sehnem 1979 for Santa Catarina, Brazil; Werff & Smith 1980 for northwestern Venezuela; and Sota 1976 for northwestern Argentina) and indices

(Reed 1954, 1965), some of which reflect uncritical or provincial acceptance of

Braun's taxonomic conclusions.

Prior to my study, 19 species of Marsilea were commonly recognized in the

New World (and Hawaii), although not all taxa were well understood. Lack of

knowledge was particularly acute for the tropical species. The primary purpose of

my study was to reconsider the existing taxonomy of the New World marsileas by

drawing on data from as many sources as possible in order to provide a new

scheme that better accounts for the known diversity in the group.

Beyond the pragmatic considerations of providing a useful modern taxonomy for this group are, of course, certain theoretical questions concerning the system atics and evolution of Marsilea that should be addressed: Do the New World

species constitute a monophyletic group? What are the relationships among

species in the genus as a whole, and of Marsilea to Regnellidium and Pilularia? What has the evolutionary history of the Marsileaceae been in geologic terms?

What were the selective forces bringing about the unfernlike characteristics of

these plants, especially the heterospores encased in sporocarps? Partial answers to these questions were available from the outset. First, the

New World species were scattered among five of the 13 species groups of Marsilea

recognized by Braun (1871), which suggests that they do not form a monophyletic group. Second, Braun's classification (Fig. 1) provides a phylogenetic hypothesis to be evaluated, as he was attempting to construct a natural classification (Braun

1871). Third, speculation on relationships among the genera of the Marsileaceae has been provided by Bower (1926), Schmidt (1978), and Wallace et al. (1984). Fourth, indisputable marsileaceous fossils of Upper Cretaceous/Paleocene age found in India (Sahni 1943; Chitaley & Paradkar 1971) and of Eocene age in

Siberia (Dorofeev 1981) show that the family was widespread and diversified by the early Tertiary and must have evolved earlier. Fifth, Wagner (1973) hypothe



1986 SYSTEMATIC BOTANY MONOGRAPHS 3

-?

fl. POLYCARPA

fl. POLYCARPA VAR. MEXICANA

y? fl- SUBANGULATA fl. PEFUEXA M. SUBTERR?NEA

?

M- QUADRIFOLIA fl. MACROPOQA M. BROWNII

M. BRACHYPUS M. GRACILENTA fl. EROSA M. CORNUTA M- CRENULATA

r M. DIFFUSA 1? M. BRACHYCARPA

fl. VIULOSA fl. TENUIFOLIA fl. MUCRONATA fl. VEST!TA fl. QNCtNATA

* -?

fl. ERN?STII fl. MEXICANA fl. BERTgROI fl. ANCYLOPODA M. MUTICA

M. CORQMANDELINA M. TRICHOPODA M. MUSCOIDES M. DISTORTA

M. STRIGOSA

M. PUBESCENS

M. EXARATA M. HIRSUTA M. ANGUST? FOL IA

M- HOWITTIANA M. SERICEA M. MUELLERI M. MACRA

jr M. OXALOIDES L M. HIRSUTISSIMA r M. NARDU

L M. DRUMMONDII jrM. SALVATRIX

L M. ELATA

M'. ROTUNDATA M. MACROCARPA M. BILOBA M. CAPENSIS M. BURCHELLII

M. AEGYPTIACA M. QUADRATA

M. GIBBA

M. GYMNOCARPA M. NUBICA

FIG. 1. Braun's classification of Marsilea (Braun 1871). The black dots indicate Braun's thirteen

species groups; the names of New World taxa are underlined.




sized that heterospory was an adaptation of proto-marsileads to rapid reproduc tion in temporary pools during wet periods in an otherwise xeric and inhospitable environment. The secondary purpose of this study was to review the evidence for

these hypotheses in light of my taxonomic work.

MATERIALS AND METHODS

Field studies and collections of Marsilea were made in Arkansas and Texas in

May, 1981, in Argentina, Venezuela, and Trinidad in winter, 1982, in Costa Rica

in August, 1982, and in Mexico in June, 1983. These trips made possible study of

the majority of New World Marsilea taxa under natural conditions. Material to be

propagated in the greenhouse was collected on all trips, as was material in the

form of dried specimens and specimens preserved in FA A or 50-70% ethanol.

Approximately 4000 herbarium sheets of New World Marsilea were examined

in the course of this study. Additional live plants were obtained by culturing spores obtained from some of specimens received on loan (see Appendix).

A collection representing up to 40 populations of Marsilea was maintained in a greenhouse at the University of Michigan Matthaei Botanical Gardens from

1981 through 1985. The plants were initially grown in pans 4 cm deep without

drainage but were later transferred to a standard potting mix in plastic pots with

drainage. All plants were grown under prevailing local day length. Voucher speci mens made from these plants are deposited at MICH. To distinguish these speci mens from those collected in the field, the collection numbers are qualified by "from cutting of. ..." Those specimens made from plants raised from sporocarps on herbarium sheets are given the parent collection number, qualified by "from

sporocarps of. ..."

Aside from functioning as a resource for anatomical, chromosome, and

chemical material, the living collection also provided cuttings that were grown in

adjacent pans, one cutting of a clone in moist soil and the other cutting of the same clone in soil under 20 cm of water in a gallon jar. The purpose of this

experiment was to observe morphological changes in leaves brought about by

development under water.

In a test for apomixis, sporocarps from 24 populations representing 12 species were obtained either from the field or from herbarium sheets. A single sporocarp was scarified and placed in a Petri dish of distilled water until the sorophore had

completely extended. The megaspores were then isolated with a pipette and trans

ferred to another Petri dish. This dish of isolated megaspores, which contained one-third to one-half of the megaspore total of the sporocarp, was then inspected for possible contamination with microspores. In view of reports of increased

production of apomictic sporophytes at higher temperatures (Bhardwaja & Ab

dullah 1972), replicate isolates and controls were kept at 37?C, while the other set was kept at 25?C. Both received 12 hours of fluorescent light per day and were

maintained for 96 hours before sporophyte production was recorded as positive or

negative.

Anatomy of petioles and rhizomes was examined by hand-sectioning and

staining with phloroglucinol-HCl. Leaf clearings followed the method used by Mickel and Votava (1971), except that stained leaves were mounted in permount




or Euparal. Pieces of rhizome, petiole, or root were examined for presence of

vessels by soaking in 10% chromic acid for 24-72 hours, rinsing, teasing apart in

70% ethanol on a slide, staining with 1% Bismark brown in 70% ethanol for a

few minutes, destaining with absolute ethanol, and mounting in Euparal. To obtain meiotic material for chromosome counts, green sporocarps ap

proaching full size were pierced with a dissecting needle, placed in a saturated

aqueous solution of paradichlorobenzene for 15-22 hours, blotted, and trans

ferred to 3:1 absolute ethanol:glacial acetic acid. The sporocarps were left in the fixative at room temperature for 2-4 hours and then placed in a freezer. After at least 48 hours, sporangia were removed from the sporocarps, cleaned of sporo carp debris, squashed in aceto-orcein, and examined under a compound micro

scope. Slides were made permanent by soaking them in absolute ethanol, remov

ing the cover slip, and then placing Euparal under the cover slip. I prepared two-dimensional chromatograms of polyphenolic compounds for

eleven taxa. Dried leaflets were crumbled by hand, placed in 70% methanol in a test tube, fragmented with a tissue homogenizer, and the supernatant spotted onto Whatman #1 chromatography paper. The chromatogram was first run in

tertiary butanol for 24 hours, dried, and then run in 45% acetic acid for 5-6 hours and dried again. For both dimensions, a rutin spot was used as a standard.

Chromatograms were then examined under UV light both in absence and pre sence of ammonia vapor.

MORPHOLOGY AND ANATOMY

The Marsileaceae as Hydrophytes

Morphological and anatomical features of the Marsileaceae have been com

pared to those of other leptosporangiate ferns many times (Bower 1926; Eames

1936; Smith 1938; Gupta 1962; Bierhorst 1971; Schmidt 1978). The conclusion reached through such comparison is typified by that of Bierhorst (1971), who

stated, "Anatomically, the stems, roots, and leaves of the Marsileaceae are rela

tively generalized in terms of ferns, even though the plants have a gross unfern like appearance."

An alternative approach to be taken here is comparison of the morphology and anatomy of the Marsileaceae to structural features and adaptations exhibited

by other rhizomatous water plants with floating leaves. Such comparisons of

morphology within aquatic angiosperms (Arber 1920; Sculthorpe 1967) have re vealed striking convergences between unrelated groups of similar life form living in aquatic habitats. Consideration of features of Marsileaceae in this way will

simultaneously point out adaptations related to life in water and provide an expla nation of the group's "unfernlike appearance."

Habit. The growth form of marsileaceous plants is generated by repetition of a uniform unit of growth, for which the term metamer is appropriate, because each unit is formed by the same meristem rather than by separate ones (White 1984). The metamer consists of an internode of creeping superficial rhizome,

which may or may not bear roots, a leaf borne laterally on the rhizome, a corre

sponding root on the rhizome at the node, and a lateral shoot arising near the leaf axil. The side of the rhizome from which the leaf and shoot depart alternates from




node to node, so that the leaves and shoots are in two ranks. The lateral shoots

vary considerably in their degree of development; in Regnellidium diphyllum Lindman and on the underwater rhizomes of Marsilea species they are suppressed and budlike, but on well-developed land forms of Marsilea they are short shoots

bearing numerous leaves. Occasionally (e.g., in M. deflexa) the laterals may grow out into long shoots with long internodes and then resemble the main shoot.

This "stoloniferous" growth habit, which is uncommon among ferns, is suited to colonizing an amphibious environment. In water it allows spread of the plant to

give room for the floating leaves on the surface, and on exposed mud it allows

rapid colonization of an unoccupied habitat in all directions. Regular production of roots and lateral shoots parallels that found in many seagrasses, in which

vegetative proliferation is often quite extensive (Tomlinson 1974; Bell & Tomlin son 1980).

As is common among aquatic plants of temperate regions, the lateral shoots

and apices of the main shoots may become sclerified and function as perennating organs (turions) in some species of Marsilea; these have occasionally been re

ferred to as tubers (Bierhorst 1971), but they do not contain an exaggerated amount of storage tissue. The lateral shoots may form their own lateral buds or

branches; Gl?ck (1922), mistaking these branches for leaves, believed them to be

cataphylls. Rhizome. The rhizome in all species of Marsileaceae is terete, and varies from

parenchymatous and glabrous in water to sclerified and hairy on land. The outer cortex is aerenchymatous, with 20-30 longitudinal air channels separated by septa 4-5 cells long and 1-2 cells wide (Fig. 2g, h); in portions of the rhizome with the same diameter but with short internodes, however, the septa may be 4-5 cells

wide and the air channels correspondingly smaller in diameter. The air channels are traversed at intervals by diaphragms composed of stellate cells (Fig. 2i), which

occasionally contain starch. Two to three layers of cortical cells immediately inside the aerenchyma zone are usually lignified, and the parenchyma of the

cortex surrounding the vascular cylinder and in the pith is, on land, filled with dark pigment, although the pith may be aerenchymatous in some species.

Air channels, unknown among other ferns except in the floating aquatic Cera

topteris Brongniart (Pal & Pal 1962), roots of the Carboniferous marattioid fern Psaronius Cotta (Ehret & Phillips 1977), the fossil rhizome Dennstaedtiopsis ae

renchymata Arnold & Daugherty (Arnold & Daugherty 1964), and the fossil

petiole Rodeites polycarpa (Chitaley & Paradkar) Chitaley & Paradkar (Chitaley & Paradkar 1971), are common features of underwater organs of vascular hydro phytes, so much so that Ogden (1974) chose them as the character with which to

define aquatic plants. Air channel diaphragms serve to resist collapse of these air

channels, reduce flooding of broken plant parts, and provide transport of nutri ents across the cortex (Tomlinson 1982). They are also common among aquatic plants and occur in Nuphar, Juncus, and Hippuris (Sculthorpe 1967), Sparganium (Kaul 1972), and Sagittaria, Hydrocleys, Limnocharis, Butomus, Scheuchzeria,

Aponogeton, and Ottelia (Tomlinson 1982), but are not known in ferns, again with the exception of Rodeites polycarpa (Chitaley & Paradkar 1971).

The vascular cylinder of Marsilea, Regnellidium, and Pilularia is an amphi phloic siphonostele with both internal and external endodermises and simple leaf

gaps. It is therefore similar to that found in dennstaedtioid and adiantoid ferns.




FIG. 2. Cross sections of a root, petioles, and rhizomes of Marsilea. (Black =

xylem; stippling =

parenchyma; hatching =

lignified tissue outside xylem; white surrounding xylem =

phloem.) a. Root

of M. macropoda. b. Petiole of M. crotophora. c. Petiole of M. macropoda. d. Petiole of M. minuta.

e. Petiole of M. ancylopoda. f. Petiole of M. mollis, g. Rhizome of M. vestita subsp. vestita. h.

Rhizome of M. deflexa, i. Interconnected stellate diaphragm cells from air channel of rhizome of M.

deflexa.

In condensed lateral shoots, however, the short internodes may give rise to a

dictyostele. Xylem maturation is reported to be exarch (Smith 1938) or mesarch

(Bierhorst 1971); frequently, however, there is only a single layer of tracheids, so that it is impossible to describe the protoxylem as being either embedded in or peripheral to metaxylem. In several species of Marsilea, and in Regnellidium, there may be discontinuities in the vascular cylinder without associated leaf traces departing, which results in a C-shaped or 3-4-parted stele (Fig. 2h). The amount of xylem in the rhizome of Marsilea varies within the genus; as in other

aquatic groups, such as the Alismatidae (Tomlinson 1982), the more aquatic members have less vascular tissue and less lignification of tracheary elements

than the more terrestrial members.

Rhizome tracheary elements in all genera are tracheids with blunt to long

tapering ends, which vary from 0.8 to 8.6 mm long and from 8 to 113 (xm wide

(Table 1); a report of vessels in the rhizome of M. drummondii A. Braun (Bhard

waja & Baijal 1977) could not be corroborated. Branched tracheids were seen in

eight species of Marsilea, where they are probably associated with nodal vascula ture. In Marsilea the larger metaxylem tracheids were pitted, but in Regnellidium



>

r w >

2 H S m 2: m

o r U

< O r C

m

Table 1. Dimensions and other characteristics of the tracheary elements in members of the Marsileaceae. Abbreviations under Plate Type, which

refers to the perforation plates of the root metaxylem elements, are SC = scalariform, SC-SI =

scalariform-simple, and SI = simple. Vouchers for the

species examined are: P. americana (Johnson 734); M. ancylopoda (Johnson 777); M. crotophora (Hatschbach & Scherer 30470, Prance et al. 26143); M.

deflexa (Johnson 778); R. diphyllum (U. M. Bot. Gard, s.n.); M. drummondii (Johnson 754); M. macropoda (Johnson 718); M. minuta (Johnson 797); M.

mollis (Murray & Johnson 1404); M. nashii (Barrington 195); M. oligospora (Farley 78-41, Ertter 3894); M. polycarpa (Johnson 784); M. quadrifolia

(Clute s.n., Ferren et al. s.n.); M. vestita (Johnson 729); M. villosa (Degener 9049).

Root metaxylem 1 (mm) w (u,m)

Rhizome metaxylem 1 (mm) w (|xm)

Petiole metaxylem 1 (mm) w (u,m)

P. americana

M. ancylopoda M. crotophora M. deflexa R. diphyllum M. drummondii

M. macropoda M. minuta

M. mollis

M. nashii

M. oligospora M. polycarpa M. quadrifolia M. vestita

M. villosa

protoxylem 6.3-6.9

2.5-4.5+

6.6-7.5

8.8

0.8-14.0+

2.4-6.4

2.7-2.8

2.2-4.3

2.0-2.9

2.6-7.1

1.7-6.1

1.4+

3.6-6.2+

1.7-6.5

30-35

35-48

23-75

30-55

40-65

33-75

33

55-69

25-53

38-48

24-48

25-28

38-55

25-53

2.6+

1.2-2.3

1.8-6.6+

0.9-1.8

5.7-6.6

1.4-5.2

1.6-4.2

2.8-5.6+

1.3-3.2+

1.3-1.6+

3.9-5.6

1.9-2.7+

6.1-8.6

0.9-3.0+

0.8-3.4+

8-13

23-35

35-75

40-53

75-113

24-33

33-68

20-83

23-40

25-35

24-38

25-45

25-43

20-35

13-38

4.3

0.6-7.8

1.1-3.5+

1.0-1.4+

22.1

2.4-12.7+

2.9-22.4+

8.9-9.7+

4.4-5.2

1.5-4.3

6.6-7.3

8.9-11.7+

8.9-9.1

8

20-53

23-118

15-58

113 48-65

18-78

35-68

28-40

18-50

38-40

20-50

63-65

21-63

53-58

Plate type sc-si si none

X X

X X

X

X X

XXX

X

X

X X

X

XXX

X X

X X

X X

Branched

tracheids

rhizome

rhizome

rhizome, petiole rhizome

rhizome

rhizome

rhizome

rhizome




diphyllum and Pilularia americana A. Braun they had sclariform or scalariform

reticulate thickenings. Tracheids in all parts of the Marsilea plant are unusually long compared to other "advanced" leptosporangiate ferns (White 1963).

Roots. In Marsileaceae the roots arise from the rhizome both at the nodes and on the internodes, although the number is variable (Schmidt 1978). Root growth is often substantial, with roots up to 50 cm long commonly being produced on

plants grown in 10-15 cm of soil in greenhouse pots with drainage. Lateral roots

may be absent or short, but in M. polycarpa and M. crotophora, which often have

floating rhizomes, the lateral roots are well developed and bear abundant hairs.

Other floating aquatics, such as species of Limnobium, Hydrocharis, Pistia, Eich

hornia, and Nymphoides, have similar plumose roots, which provide increased surface area for nutrient uptake (Sculthorpe 1967).

The roots in cross section show an epidermis bearing root hairs, an aeren

chymatous outer cortex, a parenchymatous inner cortex that is often darkly pig mented, an endodermis, and a small diarch protostele (Fig. 2a).

Metaxylem of the root consists only of tracheids in Regnellidium diphyllum and in Pilularia americana. Tewari (1975) reported vessels from Regnellidium, but

in my opinion the photographs accompanying the report are not conclusive. Ves

sel elements do occur in the root metaxylem of Marsilea, however, and were

reported in Old World species by White (1961), Mehra and Soni (1971), and

Bhardwaja and Baijal (1977). All New World species have metaxylem elements

with differentiated end walls, varying from only oblique and scalariform in M.

deflexa and M. crotophora to simple perforation plates in most species (Table 1). The vessel elements are 0.8-14.0+ mm long and 23-75 |xm wide, with pitting of

various types in the side walls. Marsilea macropoda and M. drummondii have

curious half-vessels, with a simple perforation plate present at one end and com

pletely lacking at the other.

Root vessels are found in few pteridophytes. They have been reported in

Pteridium aquilinum (Linnaeus) Kuhn (Bliss 1939), and possibly in Woodsia ilven

sis (Linnaeus) R. Brown and Notholaena sinuata (Lagasca) Kaulfuss (White

1963). In rooted aquatic angiosperms, vessels are frequently confined to the roots, but this is true of many terrestrial monocotyledons as well.

Leaves. The marsileaceous leaf is remarkable among ferns for its simple struc

ture. It consists of a petiole and four leaflets in Marsilea, a petiole and two leaflets

in Regnellidium, and an undivided phyllode in Pilularia. These leaves, especially in Marsilea, show great plasticity of form in response to a wide range of physical and chemical stimuli, such as far-red light (Gaudet 1963), C02 concentration

(Bristow & Looi 1968), protein synthesis inhibitors (White 1966), sugar concen

tration (Allsopp 1963), gibberellins (Allsopp 1959), and abscisic acid (Liu 1984). Type of leaf formed is related to size and nutritional status of the shoot apex

(Allsopp 1963), and roughly parallels the heteroblastic sequence of leaves pro duced by the young plant (Fig. 3); this sequence, corresponding to submerged,

floating, and emergent leaf types, also occurs in, for example, Sagittaria (Scul

thorpe 1967). Underwater leaves (water forms of the developmental literature) in Marsilea

vary from simple to four-parted, but are uniformly flattened, have stomata only on the adaxial surface (White 1971), and are small and delicate compared to other

leaf forms. The pulvini of the leaflets are not apparent, and the vasculature is




FIG. 3. Marsilea vestita subsp. vestita. a. Heteroblastic leaf series, b. Underwater leaves.

vestigial. Floating leaves in Marsilea and Regnellidium have long lax petioles and leaflets that lie flat on the water's surface and are splayed out in a circular

configuration. Like the rhizome, the petiole has cortical air channels separated by thin septa and traversed by diaphragms. The diaphragms in floating leaves often accumulate purple or brown pigments, giving the petiole a purple-flecked appear ance. The petiole is normally terete, but in the Australian M. mutica Mettenius the petiole has a bulbous swelling at its apex, which possibly functions in flotation

(Senn 1909). The leaflets of floating leaves are pulvinate, glabrous, and roughly fan

shaped, with water-repellent upper epidermises, straight or convex lateral mar

gins, and rounded, entire terminal margins. In cross section, the leaflets have a

uniseriate epidermis, a palisade layer, a spongy layer with included vascular

bundles, a thin region of aerenchyma, and a lower epidermis, which lacks sto mata. Hildebrand (1870) found that stomata on the upper epidermis of floating

leaves were denser than on the upper epidermis of land leaves in M. quadrifolia and M. strigosa Willdenow. Venation in Regnellidium is open dichotomous with a

connecting marginal vein, and reticulate with oblong or fusiform ar?oles in Marsi lea (Fig. 4).

Rows of abaxial epidermal cells over the intercostal areas of the floating leaflet are frequently smaller and straighter-walled than neighboring epidermal cells and, in addition, accumulate red or brown pigments. Modified epidermal cells with these characteristics, called hydropoten, also occur in both aquatic dicotyledons (Wilkinson 1979) and aquatic monocotyledons (Tomlinson 1982), where they are believed to function in uptake of salts by the leaves (Sculthorpe 1967). Wilkinson (1979) referred to the presence of hydropoten in water ferns but




FIG. 4. Venation patterns of leaflets of Marsilea. a. M. oligospora. b. M. vestita subsp. vestita. c.

M. mollis, d. M. nashii. e. M. macropoda. f. M. ancylopoda. g. M. minuta, h. M. quadrifolia. i. M.

deflexa, j. M. poly carpa, k. M. crotophora.




gave no examples. These pigmented cells, which appear as red or brown streaks on the abaxial surface of the leaflet, are considered to be hydropoten in this

paper.

Compared to the floating leaves, land leaves of Marsilea and Regnellidium are

smaller and hairier, have stiffer petioles, have abaxial stomata, may have crenate

terminal margins of the leaflets, and have proportionally smaller air channels in

the petioles. The pulvini are fully functional; they serve to orient the leaflets

during the day and cause the leaflets to fold together at night, with the abaxial

surface of the proximal pair of leaflets outermost. Pigmentation of petiolar dia

phragms and epidermal cells of the leaflets does not occur, and, in most species, a

band of fibers is present in the inner cortex of the petiole. The vascular strand of

the petiole is V-shaped or hemispherical in transverse view and bounded by an

endodermis. The xylem of the trace is V-shaped (Fig. 2b) or U-shaped with

diverging upper arms in cross section (Fig. 2c, e, f ); occasionally the two arms of

xylem are not joined at the vertex (Fig. 2d). The xylem may consist of only 5-6

tracheids in Pilularia americana but up to 100 in Marsilea macropoda. The tra

cheids are usually unbranched and pitted, with long-tapering ends, but a branched

tracheid was found in the petiole of M. macropoda. A tracheid over 2.2 cm long was found in the petiole of M. macropoda; tracheids of similar length were found

in Indian species of Marsilea by Mehra and Soni (1975) and may occur commonly in other species.

Heterophylly between land and water leaves is a common phenomenon in

amphibious plants (Sculthorpe 1967; Hutchinson 1970) and can take two forms.

Heterophylly between submersed and aerial leaves, as in Sium suave, Armoracia

aquatica, and Proserpinaca palustris, is the more common and involves general reduction and simplification of all leaf tissues in the underwater leaves. In the

second type, best exemplified by Polygonum amphibium, the dimorphy is be

tween leaves with floating and with aerial blades. Marsilea, along with Echinodo rus berteroi and Zizania aquatica (Sculthorpe 1967), is noteworthy in that its

phenotypic plasticity extends to include morphologically distinct submersed, float

ing, and aerial (land) leaves.

The only conclusion that has been reached in considering the leaves of Marsi

lea and Regnellidium as those of pteridophytes is that they are unfernlike. When

they are examined as leaves designed to float on the surface of the water, how

ever, they illustrate yet another adaptation to the restraints imposed by that life

form. Sculthorpe (1967) listed physical features that are exhibited by many float

ing leaves: circular outline of the lamina, peltate petiole attachment, entire mar

gins, pliable petiole, water-repellent thickened adaxial epidermis, radial arrange ment of laminar veins, buoyancy provided by aerenchyma, regular arrangement of spongy mesophyll cells, and stomata only on the upper epidermises. The physi cal characteristics are seen as modifications optimizing flotation of the laminar

surface while minimizing the effects of stresses imposed by water movement. The

pliable petiole allows reposition of the leaf with a change in water depth or

available open surface area. Waterlilies approximate the circular form and peltate attachment by expansion of the lobes of a cordate leaf; in Marsilea and Regnellid ium, the separate leaflets of one leaf together approximate the circular form and

outline and diverge from a common center, which provides the peltate configura tion. The floating leaflets of the two genera exhibit a small amount of aeren




chyma, water-repellent upper surfaces, and absence of abaxial stomata. Selection in the evolutionary history of the Marsileaceae may thus be seen as having fa vored a leaf of a form adaptable to functioning as a floating leaf; because of the

developmental constraints this design placed on the leaf, the appearance of the land leaf would have been influenced as well.

Sporocarp. Like many aquatic plants, Marsilea produces its reproductive structures out of water; only M. deflexa and M. berhautii Tardieu are known to

form sporocarps regularly underwater, although M. quadrifolia, M. ancylopoda, and M. vestita occasionally do so. The production of sporocarps is probably phy

siologically linked to illumination (Allsopp 1951), so that photosynthate reaching submerged rhizomes may be more of a factor than the presence of water itself.

Sporocarps of all Marsileaceae are borne on leaf rachises called peduncles (the terms pedicel, stipe, stalk, and carpopodium have also been applied to these

structures). The peduncles are attached to the petiole at or considerably above its

base; in M. crotophora, which may have up to 20 sporocarps per leaf, the upper most sporocarp is usually borne distal to the midpoint of the petiole. The pedun cle may be branched or unbranched, and in the Old World species M. minuta and

M. botryocarpa F. Ballard both types may occur on the same leaf.

The sporocarps begin to develop later than the attached leaf and often do not

mature until after the leaf has withered and broken away. When immature, sporo

carps are hairy, chlorophyllous, and leathery, but when mature they often lose the

hairs and become hard and brown or black. Mature sporocarps are bilaterally

symmetrical, and may be discoid or globoid, and up to 9 mm long, 6 mm wide, and 2.5 mm thick. The hard wall, consisting of a cutinized epidermis, two layers of columnar sclereids, and a layer of I-shaped cells (Fig. 8), insures the viability of

the contents over long periods of time (Allsopp 1952; Johnson 1985b). Internal to the wall layers and just below the upper edge of the sporocarp is

an in verted-V-shaped trace surrounded by chlorenchyma. Lateral veins branch

from this median trace at intervals along its length and supply the branched or

unbranched receptacles of the sori, which may number 2 to 25 per sporocarp. The

sori are also attached to a mass of gelatinous tissue, the sorophore, just below the

median trace, and are torn from their vascular moorings when the sorophore becomes hydrated, thereby expanding and pushing the sori out of the sporocarp.

Although it contains spores rather than seeds, the marsileaceous sporocarp is similar to fruits common among aquatic angiosperms. The presence of hygro

scopic tissue to aid in dehiscence of the propagule, while uncommon among

hydrophytes, is also found in the fruits of the floating-leaved genera Nuphar,

Nymphoides, Hydrocharis, and Stratiotes, in which bursting of the fruit is

achieved by expansion of a mucilaginous pulp or seed coat (Arber 1920). Once the contents of the sporocarp are hydrated, development of the gameto

phytes takes place quickly, with sperms released by the microgametophytes after

only five hours (Rice & Laetsch 1967). Fertilization takes place within 24 hours, and the embryonic sporophyte grows rapidly, being supplied by abundant nutri ents contained in the attached megaspore. The first root and leaf are visible after 2-3 days, and additional leaves in a relatively uniform heteroblastic series form

rapidly. Conclusion. These comparisons demonstrate that convergences between the

Marsileaceae and other rhizomatous aquatic plants with floating leaves are nu




merous, and suggest that evolution toward the aquatic habit was a major force in

molding the specialized vegetative morphology and reproductive biology of these

plants. All members of the family share a complete suite of aquatic adaptations, with these adaptations retained even among the more terrestrial species that have

densely hairy leaves and sclerified rhizomes. In these cases, the adaptations to

ward passing a greater portion of the life cycle on land are secondarily acquired, rather than primitive, being superposed on a plant form and life cycle designed for life in water. Anatomical and morphological features of the family shared with

other leptosporangiate ferns being "relatively generalized" suggest that the Marsi

leaceae diverged early from other fern groups.

Systematic Considerations

Because of the simplicity of form of members of the Marsileaceae, characters of plant parts that are useful in systematics are few and subtle. Predictably, in the

search for taxonomic characters past workers have seized upon some characters

that are exceedingly variable, either from a genetic or environmental standpoint. In this section I discuss and evaluate characters that have been used systematically in Marsilea and identify the ones I found to be most useful and reliable.

The relative development of roots and lateral shoots varies within the Marsi

leaceae and provides characters of systematic importance. Schmidt (1978) pointed out the fundamental difference in root position and number between Marsilea and

Pilularia on the one hand and Regnellidium on the other. Regnellidium has nu

merous roots disposed in two rows along the internodes as well as roots at the

nodes. Schmidt also claimed that in Marsilea and Pilularia single roots were

present only at nodes, the apparent clusters of roots at the nodes being the result

of nodal roots on the greatly condensed lateral shoots. In examining this further,

however, I found that, while this pattern holds for Pilularia and for many species of Marsilea, there are other species of Marsilea that also have 1-3 internodal

roots, and that this character is stable enough within large groups of species to be

systematically useful. Variability in this character occurs in the direction of species that normally lack internodal roots and have the nodal roots occasionally offset a

short distance into the internode, as in M. mollis and M. ancylopoda; the reverse

is almost never the case. At a local floristic level, this character is useful in

identifying sterile specimens, as in separating M. vestita from M. quadrifolia

(Johnson 1985a), and M. ancylopoda from other Venezuelan species o? Marsilea.

Degree of development of the lateral shoots, a character also found in the

aquatic genus Lilaeopsis (Umbelliferae) (Affolter 1985), can be taxonomically

helpful, and in New World marsileas it seems to be associated with restriction of roots to the nodes. If the lateral shoots are largely suppressed, only 2-3 leaves

will appear to be present at a node, whereas in plants with well-developed lateral

shoots a tufted appearance of 10-15 leaves will occur. This clustered growth pattern becomes even more pronounced if the internodes on the main shoot are

short. Members of Marsilea sect. Nodorhizae commonly exhibit this growth form on land, while species of sect. Marsilea and sect. Clemys have a diffuse pattern of

growth with scattered leaves. This difference can be taxonomically useful, but the

warning given by Affolter (1985) concerning the same character in Lilaeopsis

applies in Marsilea: "Because the character varies among species, it is taxonomi

cally significant. Because it is plastic, it must be employed with caution."




Characters of internode length, rhizome diameter, and rhizome anatomy do

not seem taxonomically useful, although a trend in the reduction of rhizome

vascular tissue is generally apparent, with the more aquatic species having a

smaller number of tracheids in cross section. Petiole anatomy offers slightly more

information if similar environmental morphs are compared; again number of

xylem cells is correlated with occurrence in drier habitats, and there is variation in

the shape of the vascular trace. A cortical fiber band was observed in land leaves

of all species studied except M. quadrifolia and M. minuta, which confirms a

relationship between those two species suggested by other characters.

The leaflets of Marsilea are notoriously plastic in shape and can vary widely within species (Fig. 5); conversely, leaf venation varies little within the genus

(Fig. 4). Leaflet characters have thus been largely ignored in Marsilea taxonomy, with the exception of the false veins of sclerenchyma in several African species

(Launert 1968) and the exceptionally narrow leaflets of M. angustifolia R. Brown

and M. tenuifolia [-M. vestita subsp. tenuifolia] (Braun 1871). Another leaflet character that has been used taxonomically is the presence of

red abaxial streaks on the leaflets of M. mexicana [=M. mollis] (Knobloch &

Correll 1962; Stolze 1983; Lellinger 1985). As was suspected long ago, however, these streaks, or hydropoten, as they are considered here, are not constant fea tures of certain species or even individuals; F?e (1857) suggested that they were

"accidental" in occurrence, Braun (1871) and Senn (1909) discussed their occur rence on floating leaves, and, more recently, Mickel and Votava (1971) noted the occurrence of these streaks on leaflets lacking abaxial stomata.

In order to demonstrate conclusively the inconstant nature of hydropoten, I

grew plants of M. ancylopoda, M. crenata, M. deflexa, M. drummondii, M. ma

cropoda, M. macropoda x vestita, M. mollis, M. nashii, M. quadrifolia, and M. vestita subsp. vestita in 20 cm of water in gallon jars for five weeks. All formed

floating leaves, and all developed streaks on the leaflets. The streaks appeared as

shiny colorless areas on the epidermis of newly formed floating leaves, but turned dull red or brown several days prior to senescence of the leaves. No streaks formed on leaflets of nearby control plants grown out of water. Although the

physiological basis for the phenomenon cannot be determined from the results, the experiment demonstrates that the capacity to produce hydropoten is not lim ited to one species and on the contrary appears to be a characteristic common to all species of Marsilea.

In spite of the plastic nature of the leaves, there seem to be minor but consistent differences in the shapes of the leaflets, which can be useful in separat ing species as long as only land leaves are compared. These differences have to do

with leaflet width, curvature of the lateral margins, and leaflet symmetry (Fig. 5). Marsilea mollis and M. vestita subsp. vestita overlap slightly in range, are difficult

to distinguish, and are often collected in sterile condition. The leaflets of M. mollis are regularly more symmetrical than those of M. vestita subsp. vestita,

although both may vary considerably in shape (Fig. 5). Likewise, M. macropoda, which is ordinarily readily distinguished from its congeners by its large size, has

relatively broad leaflets with strongly concave margins even in small specimens. Leaflet stomatal patterns have received attention as being of potential taxo

nomic use in Marsilea (Gupta 1957, 1962; Mickel & Votava 1971; Van Cotthem

1973). Mickel and Votava (1971) concluded that stomatal size and density and




FIG. 5. Outlines of leaflets of species and hybrids of Marsilea. a. M. macropoda. b. M. macro

poda x vestita. c. M. vestita subsp. vestita. d. M. vestita subsp. tenuifolia. e. M. nashii. f. M. vestita

subsp. vestita. g. M. mollis, h. M. oligospora. i. M. ancylopoda. j. M. deflexa, k. M. polycarpa. 1. M.

crotophora. m. M. minuta, n. M. quadrifolia.

subsidiary cell configuration were too variable to be of taxonomic use in the New

World species of Marsilea, except perhaps for the diacytic condition that seemed

to characterize M. nashii and M. tenuifolia [=M. vestita subsp. tenuifolia]. They noted that these two species had the narrowest leaflets of the species they exam

ined. In studying this further I found that in broader leaflets of M. nashii there was a transition to the anomocytic stomatal pattern found in other marsileas (Fig.

6), even though leaves with narrow leaflets from the same plant showed the

diacytic arrangement. A developmental correlation between narrow leaflets and

the diacytic pattern therefore seems possible. These observations cast further

doubt on the taxonomic value of stomatal characters in Marsilea.

Mickel and Votava (1971) also reported that specimens of M. mexicana [=M.

mollis] had the highest stomatal densities of the 13 Marsilea species they examined.

In studying their voucher specimens, I noted that both of their specimens of "M.

mexicana" had only floating leaves; in view of the findings of Hildebrand (1870), it

is not surprising that a higher density of stomata was found on the adaxial surface of

the leaflets. This point underscores the necessity for comparing leaves formed

under the same environmental conditions in taxonomic studies of Marsilea.




FIG. 6. Marsilea nashii. Narrow (a) and broad (b) leaflets with corresponding stomata.

Distinctive trichomes are found on land leaves, land rhizomes, and sporocarps of all Marsileaceae. They consist of two small stalk cells, a triangular cell attached

with its long axis perpendicular to the stalk cells, and one to seven additional cells

forming a "tail" to this triangular "head" cell (Fig. 8). The hair structure is fairly uniform throughout the family, although some species have trichomes with ex

tremely long hyaline tails or with conspicuously verrucose cells, but in general the

trichomes are too variable to provide a source of taxonomic data as hoped by

Gupta (1962). The lone exception to this is the presence of basally attached

uniseriate trichomes in the African M. farinosa Launert (Launert 1968). The sporocarp has provided the basis for all past taxonomic work on Marsi

lea. The sporocarps are variable in their attachment to the leaf by branched or

unbranched peduncles, which may be at or above the petiole base, and in num

ber, varying from a single sporocarp in many species to 26 per leaf in some

specimens of M. poly carpa. As mentioned previously, the sporocarps usually

persist long after the associated leaf has withered. This had led to description of

sporocarps in some species of Marsilea as being borne directly on the rhizomes

[e.g., Correll & Correll 1975 for "M. mexicana," Launert 1968 for M. strigosa, and Launert 1971 for M. glomerata Launert (non M. glomerata Presl)]. I mention

this to emphasize that the sporocarp is always foliar, and in addition, that it is

only part of the leaf. This foliar nature of the sporocarp has been confirmed by the anatomical studies of Allison (1911) and Bierhorst (1971), who showed that

the sporocarp traces depart laterally from one arm of the petiolar vascular strand

in the manner of a pinna trace. The attachment is often difficult to discern,

however, in species with the sporocarp attached at the petiole base, where the

departure of the leaf from the rhizome may be obscured by trichomes or other

leaves.

The peduncles are variable in length, branching, and orientation. They may be virtually nonexistent, as in M. strigosa, or up to 60 mm long in M. drummon

dii. They are always unbranched in the members of sect. Clemys, which usually have more than one sporocarp per leaf, but are branched, unbranched, or both in

other species with poly-sporocarpic leaves, such as M. botryocarpa, M. m?galo




manica Launert, M. macropoda, M. minuta, and M. quadrifolia. The peduncle is

often twisted, and in M. distorta A. Braun, M. subterr?nea A. Braun, M. vera

Launert [non M. vera Jarmolenko], and M. ancylopoda it is positively geotropic, with the sporocarps thus being produced and maturing underground, not unlike

the fruit of Arachis (peanut). Peduncle length can be useful taxonomically, as it usually has fixed limits

within a species, but it is plastic environmentally and should be used carefully.

Bhardwaja (1967) found that growth in shallow water caused lengthening of the

peduncles in M. minuta. I have observed increase in peduncle length associated

with growth in crowded conditions in M. vestita and M. mollis.

The sporocarp itself provides additional surface and internal features of taxo

nomic use (Fig. 7). The trichomes, which are often most elaborately developed on

the sporocarp, vary from long silky ones in M. macropoda to short blunt ones in

M. vestita, but with species usually exhibiting considerable variability in this re

gard. The superior tooth of the sporocarp is absent in some species (M. macro

poda), usually absent in others (M. oligospora, M. mollis), and present and

conspicuous in still others (M. quadrifolia, M. nashii). The inferior tooth can vary from present to absent within a species. The presence or absence of a raphe, in

contrast, is much less variable, being found in all species with the exception of

members of sect. Clemys.

Sporocarp shape is fairly uniform and reliable within species, more so than

sporocarp size. An exception is M. ancylopoda, for which shape of the sporocarp is somewhat dependent upon the degree of resistance offered by the substrate to

the enlargement of the sporocarp. Extremely small but otherwise typical sporo

carps were observed in specimens of M. ancylopoda and M. vestita.

The sporocarps also vary in internal structure. The epidermis is uniseriate in most species (Fig. 8a, b), but in M. vestita and M. macropoda it is 2-5 cell layers thick between the trichome bases and appears as "humps" in cross section (Fig. 8c). The wall layers of columnar sclereids are constant, but the layer of I-shaped cells is indistinct in some species. Venation of the sporocarp was emphasized by Braun (1871) and provides another character distinguishing the members of sect.

Clemys from the rest of the genus. Members of this section have the lateral veins of the sporocarp intersected by a transverse vein near the point of attachment of the soral veinlets; such a connection is lacking in other species, which may, however, have occasional anastomoses between adjacent lateral veins (Fig. 9).

Sorus number seems to be correlated with sporocarp size in Marsilea, and thus does not provide additional systematic information. Likewise, number of

megasporangia and microsporangia per sorus seems related to the size of the

sorus, which is in turn reflected by sporocarp size; an exception to this correlation is the relatively low numbers of megaspores per sorus in M. oligospora.

Marsilea microspores are globose, with thin walls and trilete laesurae. They may be weakly cristate, granulate, or reticulate externally, but ornamentation varies even within the contents of a sporangium. The microspores are remarkably uniform in size between species. Within M. ancylopoda the range in microspore diameter is 50-80 |xm; among all New World species the range is 50-85 |xm. Number of microspores per sporangium is variable, but within an individual sorus

rather than between species. All species produce a few abortive microspores,




FIG. 7. Sporocarps of Marsilea vestita subsp. vestita (a) and M. deflexa (b).

these being either small, brown, and irregularly shaped, or large, globose, and

thin-walled, the former being the more common.

Megaspores in Marsilea are radiosymmetric and ovoid to nearly globose in

shape. Again neither characteristics of spore size nor of wall sculpture are diag nostic of species. All megaspores of New World species of Marsilea are 400-740

jxm long and 320-580 jxm wide, with a domeshaped apical papilla that is 40-80

(xm long and hemispherical to pentagonal in lateral view. Wall sculpture of the

megaspores of these species is smooth, granulate, or indistinctly reticulate. The sporocarp has always been the central feature in Marsilea systematics,

but the emphasis on its specific characters has shifted from worker to worker.

Gupta (1962), in his monograph of Marsilea, dismissed the characters of sporo carp venation and ornamentation used by Braun; he followed Baker (1886) and claimed greater systematic importance for the position of attachment of the sporo carps. The observations presented here, however, suggest that, on the contrary, the sporocarp itself offers the more reliable characters, which are then supported by additional non-sporocarp characters. For example, Gupta (1962) followed Braun (1871) and Baker (1886) in placing M. macropoda in a group with M.

quadrifolia and M. brownii A. Braun [=M. mutica] on the basis of their branched

peduncles. M. macropoda differs from those two species in having larger sporo carps with more sori, densely hairy rather than glabrate sporocarps, and a multi seriate sporocarp epidermis. In these characters it resembles M. vestita, which

always has an unbranched peduncle but which shares additional characters with M. macropoda, namely the production of xanthone glycosides and the absence of

internodal roots. This relationship had been obscured by an overemphasis on

sporocarp attachment in Marsilea classification.

PUTATIVE HYBRIDS

In the course of this study I encountered several uncommon taxa that were

morphologically intermediate between species, which suggested to me that they




FIG. 8. Cross sections through walls of sporocarps of Marsilea. a. M. minuta, b. M. deflexa, c.

M. macropoda.

were hybrids. Stace (1980) summarized five criteria for recognition of hybrids: 1)

intermediacy (chromosomal, chemical, or morphological), 2) reduced fertility, 3) F2 segregation, 4) distributional evidence, and 5) artificial resynthesis. All of the

following putative hybrids exhibit varying degrees of intermediacy and occur

within the ranges of the putative parents. Reduced fertility was difficult to assess

from herbarium material, as spore morphology and viability in Marsilea are sub

ject to environmental effects such as reduced light and temperature (Shattuck

1910); in addition, normal megaspores may appear shrunken and non-viable if

sporocarps are collected while immature. The only known attempt at artificial

synthesis of Marsilea hybrids failed (Buchholz & Selett 1941). In the following discussion I present evidence supporting recognition of three

putative hybrids among New World marsileas. Two of these are between mem

bers of sect. Clemys and occur in northwestern South America, and the other, which is known from Texas, is between M. macropoda and M. vestita in sect.

Nodorhizae. To illustrate intermediacy of specimens, I chose characters in which

the putative parents differed most widely, and calculated means and standard

deviations for them. Citation of specimens, nomenclatural matter, and ecological information for the hybrids are found in the section Taxonomy.

Opportunity for interspecific hybridization in Marsilea arises when sporocarps of two species dehisce in close proximity to each other. This may happen either

prior to dispersal, when the species are growing sympatrically, or following dis

persal, when sporocarps of one or both species are dispersed into the same habi

tat. Only once have I seen two species of Marsilea growing together (M. deflexa and M. ancylopodd), and I found no evidence of hybridization. Sympatry may be

promoted by flooding of Marsilea habitats during the wet season; in northwestern




FIG. 9. Venation of sporocarps of Marsilea. The vein pattern shown for each species represents the thick midvein along the top and the lateral veins on one side of the sporocarp. a. M. oligospora. b.

M. macropoda. c. M. ancylopoda. d. M. deflexa, e. M. crotophora.

South America, Marsilea plants commonly grow on floating mats of vegetation dominated by Eichhornia, which move about and could bring different species in

contact with each other.

Members of Marsilea sect. Clemys all have a row of sporocarps on the petiole; these sporocarps vary in number, size, and position (Table 2). Both hybrids between members of sect. Clemys appear to involve M. deflexa, which has a mean

number of sporocarps per leaf of 2.08, a mean height of the lowest sporocarp above the petiole base of 3.00 mm, and a mean sporocarp length of 4.90 mm.

Both of the species with which it hybridizes have larger numbers of sporocarps

per leaf, sporocarps attached higher above the petiole base, and smaller sporo

carps. In the first of these two species, M. crotophora, mean number of sporo

carps per leaf is 13.00, mean height of lowest sporocarp is 37.72 mm, and mean

sporocarp length is 3.20 mm. In the hybrid between M. crotophora and M. deflexa the mean number of sporocarps per leaf is 5.83, mean height of the lowest

sporocarp above the petiole 6.40 mm, and mean sporocarp length 3.22 mm.

Although the sporocarps of the hybrid are approximately equal in length to those

of M. crotophora, they are not as wide and are more angular in cross section (Fig.

12). This hybrid is known from five collections and two localities, one in Colom

bia and one in Venezuela. In Colombia it occurs near localities for M. deflexa;

although M. crotophora has not yet been collected in Colombia, I expect it there on the basis of its occurrence in southwestern Venezuela.



to

2 >

r m >

2 H X W

m

o r ?

< O r d

m

Table 2. Means and standard deviations for putative hybrids and parents in Marsilea section Clemys (above) and in Marsilea section Nodorhizae

(below). The number of samples is the same for all characters unless otherwise indicated.

M. crotophora M. crotophora x M. deflexa

(M. xsubangulata) M. deflexa M. deflexa x M. polycarpa M. polycarpa

11

,4,5

13

5

14

sporocarps/leaf

(x ? SD)

13.00 ? 5.49

5.83 ? 2.70

2.08 ? 0.95

2.40 ? 0.55

12.57 ? 6.63

height of lowest sporocarp above petiole base in mm

(x ? SD)

37.72 ? 24.41

6.40 ? 1.78

3.00 ? 0.92

4.54 ? 1.90

14.99 ? 9.85

sporocarp length in mm

(x ? SD)

3.20 ? 0.38

3.22 ? 0.37

4.90 ? 0.52

2.82 ? 0.16

2.35 ? 0.18

M. macropoda M. macropoda x M. vestita

M. vestita

11

9, 10

20

angle of sporocarp to peduncle in degrees

(x ? SD)

126.8 ? 14.5

101.1 ? 10.5

93.0 ? 18.5

leaflet width in mm

(x ? SD)

16.15 ? 5.62

10.60 ? 3.36

6.93 ? 3.85




Specimens of this hybrid were originally described as a species, Marsilea

subangulata, by Braun (1871), who remarked upon its morphological intermedi

acy between M. deflexa and M. polycarpa. As will be clear from the description of

the next hybrid, the slightly larger sporocarps attached higher above the base of

the petiole of M. x subangulata suggest M. crotophora, a species unknown to

Braun, rather than M. polycarpa as its second parent. In the second hybrid the mean number of sporocarps per leaf is 2.40, very

close to that of M. deflexa. The mean height of the lowest sporocarp, however, is 4.54 mm, and mean sporocarp length is 2.82 mm. For M. polycarpa the

mean number of sporocarps per leaf is 12.57, mean height of the lowest sporo

carp is 14.99 mm, and mean sporocarp length is 2.35 mm. The hybrid shares

with M. polycarpa sporocarps that are rounded rather than angular in cross

section.

A two-dimensional chromatogram of polyphenolic compounds for M. poly carpa showed only a single compound, that for M. deflexa showed four com

pounds, and that for a specimen of their putative hybrid {Johnson 792) showed

five compounds. The positions of the spots on the chromatograms suggested that

the hybrid was combining the polyphenolics present in its putative parents, but

insufficient quantities of material were available to identify the compounds. This hybrid is known from only two collections, both from Apure in south

western Venezuela. The range of the hybrid is within the ranges of the parents,

although neither was found growing with it.

Several specimens of Marsilea from central Texas combined the robust hairy leaves of M. macropoda and the prominent superior tooth of the sporocarp found

in M. vestita. The sporocarps of M. macropoda are strongly ascending, diverging at a mean angle of 126.8? from the peduncle, while those of M. vestita are slightly

nodding to slightly ascending, diverging at a mean angle of 93.0? (Table 2). The

sporocarps of the hybrid specimens are slightly ascending, diverging at a mean

angle of 101.1?. Mean leaflet width, which provides a measure of leaflet size, is

16.15 mm for M. macropoda, 6.93 mm for M. vestita, and 10.60 mm for the

hybrid. The hybrid is known from seven collections, all from within the ranges of one or both putative parents, but again I have no evidence of the hybrid's growing with either parent.

LIFE-HISTORY CHARACTERISTICS OF MARSILEA

Many ferns are difficult to grow, even in culture, and may take several years to reach maturity. The tiny spores do not lend themselves to field studies of

dispersal, dormancy, and persistence in a seed bank nor is establishment easy to

monitor, because fern gametophytes are both delicate and difficult to identify. For these reasons, few fern life histories are well known (Farrar & Gooch 1975;

Watt 1976; Harper 1977), and comparisons with angiosperms are difficult.

Marsilea, however, has a dispersal unit, the seedlike sporocarp, that is macro

scopic, long-lived, and easy to recognize. Its gametophyte is ephemeral, and the

attached sporophyte, supplied with stored food from the megagametophyte, de

velops 24-48 hours after germination. The young sporophytes are easy to recog




nize and fast-growing. These features allowed me to study certain life-history characteristics of Marsilea and to compare them with those of angiosperms.

Marsileas generally grow in shallow water or on open shores in full sun; shaded plants are often sterile. The plants seldom persist in one locality for long

periods of time; I was often unable to locate populations of M. vestita and M.

macropoda at localities where they had been collected 8-10 years earlier. A

population of M. vestita in Faulkner County, Arkansas, observed through the

growing seasons of 1981-1984, showed vigorous growth and abundant sporocarp

production in 1981 but then gradually declined. By 1984, when the site had

become shaded by willows and invaded by grasses, the Marsilea colony was

diffuse and was producing no sporocarps. These observations suggested that

Marsilea, unlike many pteridophytes, is a colonizing plant. To examine this idea

further, I reviewed other aspects of the life-history of Marsilea.

Reproduction and Dispersal. Marsileas have two potential long-distance dis

persal units. One of these is the dormant rhizome apex, which can break from

the plant and be carried by water. As most marsileas do not occur in lotie

habitats, however, the potential for rhizome apices to act as long-distance dis

persal units is limited; these apices might not withstand desiccation long enough to allow them to be transported by simple adhesion.

The second dispersal unit is the sporocarp, which is durable and can remain

viable for up to 100 years (Johnson 1985b). Sprocarps can be transported by

simple adhesion (Quisumbing 1924), or they can be ingested. Malone and Proc

tor (1965) demonstrated that sporocarps of M. vestita would pass intact through the digestive tract of the wood duck (Aix sponsa Linnaeus), and Proctor (1968) further showed that sporocarp-sized propagules, such as seeds of Desmodium,

Celtis, Rhus, and Cassia, might be ingested by shorebirds, carried long distances, and regurgitated intact. Sporocarps of Marsilea have been found in the crops of

the ducks Anas platyrhynchos Linnaeus (McAtee 1918), A. acuta Linnaeus

(Mabbott 1920), A. clypeata Linnaeus (McAtee 1922), and Aythya marila (Lin

naeus) (Kubichek 1933), and the shorebirds Charadrius vociferus Linnaeus

(DeVlaming & Proctor 1968), Himantopus mexicanus (M?ller), and Recurviros

tra americana Gmelin (Wetmore 1925) in North America. Frith (1982) reported the following Australian waterfowl to feed on Marsilea: Dendrocygna arcuata

(Horsfield), D. eytoni (Eyton), Stictonetta naevosa (Gould), Anas superciliosa Gmelin, A. gibberifrons M?ller, A. rhynchotis Latham, Oxyura australis Gould, and Biziura lobata (Shaw). Of these, only Biziura lobata ate appreciable quanti ties of Marsilea. All of these birds are migratory, the North American species

particularly so. I found that the Mexico-Andes range disjunction of Marsilea

mollis is a common pattern among flowering plants dispersed by birds (Cruden

1966), and that the range of M. vestita is concentrated over the Pacific and

Central fly way s of North America.

Thus I suggest that bird dispersal is probably a factor affecting distribution in

many Marsilea species. Marsilea ancylopoda, however, produces its sporocarps

underground in mud that hardens when dried. This may render the sporocarps less accessible to dispersers, and in fact distribution of this species does not

correspond to bird migratory patterns. The durability of sporocarps allows their persistence through inhospitable




conditions and may also increase chances for outcrossing by allowing a diversity of

genotypes to build up in a "seed bank." Sporocarps are relatively large among

propagules with long dormancies, but Harper (1977) mentioned that aquatic

plants may exhibit this deviation; examples, such as Nelumbo, were listed by

Sculthorpe (1967). Apomictic production of sporophytes from megagametophytes was reported

by Bhardwaja and Abdullah (1972) in several Old World species of Marsilea, and

to a limited extent in M. vestita by Mahlberg and Baldwin (1975). I conducted

tests involving culture of isolated megaspores from herbarium specimens for most

of the New World taxa to document additional instances of apomixis. The results

I obtained did not suggest existence of apomixis in the species examined (Appen

dix), but formation of sporophytes in control dishes containing the contents of a

single sporocarp did indicate that six species were self-compatible. Negative re

sults must not be taken as conclusive evidence against self-compatibility, however, as other sporocarps from some of the collections that formed no sporophytes have

yielded abundant young plants on other tries. Self-compatibility would enable a

new Marsilea population to be established by a single sporocarp, an attribute that

increases the probability of reproduction following long-distance dispersal (Baker

1955). Growth and maturation of young plants is rapid, with sporocarp production

beginning in greenhouse plants of M. ancylopoda less than three months after

germination; sporocarp production then proceeds more or less continuously, al

though some species in cultivation showed reduced sporocarp production during the winter. Marsilea mollis represented the other extreme, with only two of seven

samples in the greenhouse ever producing sporocarps, and then only for 1-2

months within a two-year period. Sporocarps are produced only on land in most

species, but M. deflexa commonly forms them under water as well.

Limitations upon Growth and Reproduction. Plants of M. vestita subsp. vestita

from Texas and Oklahoma, and of M. ancylopoda, M. deflexa, M. drummondii, M. ephippiocarpa Alston, M. macropoda, M. minuta, and M. mollis, grew con

tinuously in the greenhouse with thinning and repotting, some of them for over

four years. Plants of M. quadrifolia, and of M. vestita subsp. vestita from Montana

and California, however, exhibited a day-length-dependent dormancy in the

greenhouse. Production of new growth from lateral buds on old rhizomes of M.

quadrifolia was also observed in the field.

In all species of Marsilea the lateral shoots at the nodes develop, mature, and

begin to produce leaves and roots in a continuous process. This regular increase in

the number of active meristems, as mentioned in the discussion of morphology and anatomy, allows the Marsilea plant to proliferate rapidly in an open habitat. Extent of root and lateral shoot production is variable in the genus, however, and correlated with habitat differences. Species such as M. quadrifolia and M. deflexa,

which grow in continuously wet sites and become dormant or die when the habitat

dries, have shallow roots produced on all parts of the rhizome, and lateral buds that are dormant or that bear only one or two leaves until they grow out into

rhizomes resembling the main shoot (Fig. 10a). In other species, such as M.

macropoda and M. ancylopoda, found in sites that often dry out periodically, the

deeply penetrating roots are produced only at the nodes, and the buds grow out at




FIG. 10. Growth patterns in Marsilea deflexa (a) and M. ancylopoda (b).

once into short shoots bearing 3-10 leaves and an equal number of roots (Fig. 10b). The main rhizome thus functions as a stolon that propagates and "spaces" clusters of leaves and roots. Intermediate morphologies occur; the African M.

ephippiocarpa has shallow roots along the entire rhizome, but also short lateral shoots bearing numerous leaves.

Water level thus appears to be a limiting factor for some species. For ex

ample, M. deflexa and M. ancylopoda occurred along the margin of the same

drying pond in northwestern Venezuela; M. ancylopoda occupied the dried upper

portions and muddy edges of the pond, while M. deflexa was confined to the shallow water and perished quickly as the mud in which it was growing dried.

The significance of variation in other ecological parameters is less clear. In most Marsilea habitats I studied, the soils were clays of pH 5-9; exceptions to

growing on clay soils included populations of M. minuta growing on sandy soils in

Trinidad, and M. quadrifolia growing on an alluvium of sand, silt, and gravel in




Michigan. Occurrence on soils high in sand and gravel was also reported by Kotenko (1976) for M. vestita subsp. ves tita in Montana. In situations where

Marsilea species grew in sandy soil, moisture levels were high, suggesting that the

water-retaining properties of clay soils may normally be significant to persistence of Marsilea plants.

Competitive effects on Marsilea growth by other plants are hard to assess

without experimental evidence. Although most species seem intolerant of shade or crowding, M. minuta in Trinidad formed extensive stands of abundantly fertile

clones under coconut trees, where it grew intermixed with other low rhizomatous

plants; similarly, a population of M. quadrifolia in Michigan has maintained its

size for several years intertwined among the rhizomes of Sparganium eurycarpum and Peltandra virginica in a shaded river backwater.

No major impact of predators on growth and reproduction of Marsilea was

noted in the 50 populations, representing nine species, examined. Larvae of the

generalist noctuid moth Spodoptera exigua (H?bner) and of an unidentified

pyralid moth were found feeding on the leaflets of M. vestita subsp. vestita at the

Arkansas site in 1983. The generalist Spodoptera litura (Fabricius) has been

reported to feed on M. quadrifolia in India (Sain et al. 1983). Several species of

weevils (Curculionidae) are known to oviposit in sporocarps (Board & Burke

1971; Loyal & Kumar 1977), with the larvae developing inside; I occasionally observed oviposition damage on herbarium specimens that may have been

caused by such weevils.

The life-history of the aquatic heterosporous fern Marsilea shares many char

acteristics with those of weedy seed plants, such as long propagule dormancies,

self-compatibility, rapid growth, and occurrence in early successional habitats.

Marsilea differs markedly from homosporous ferns in its use of biotic rather than

abiotic dispersal agents, longevity of spores, and lack of dependence upon a

delicate, long-lived, photosynthetic gametophyte stage for establishment. I con

sider the morphology of the Marsilea plant to be important in allowing it to

function as a colonizer, and that further specializations in this morphology are

associated with a range of habitat preferences among Marsilea species.

PHYLOGENY

The Marsileaceae are an isolated group without close living relatives. Al

though they share many features with terrestrial pteridophytes, their origin is

difficult to trace in geologic or phylogenetic terms. It is further difficult to postu late, convincingly, intergeneric and interspecific relationships within the family. In

this section I review these phylogenetic problems in light of my taxonomic studies of Marsilea.

Relationships within the Marsileaceae. The New World species of Marsilea have never been recognized as forming a monophyletic group. In Braun's classifi

cation of Marsilea (1871), the only complete infrageneric classification available, the species currently known to be present in the New World fall into five of the 13

species groups (Fig. 1). While my study did not allow me to evaluate Braun's

phylogeny of Marsilea entirely, I had enough data to consider the species groups




in which New World species occur. I found it possible to define these groups better through the use of taxonomic criteria different from those used or empha sized previously.

Braun based his Marsilea polycarpa group on vein anastomoses in the sporo carp. I exclude M. subterr?nea, because its vein anastomoses only occur near the

tip of the lateral veins rather than in the middle, and because its sporocarp has a

raphe and a long basal peduncle, but I agree that the remainder of the group

represents a monophyletic line within Marsilea. I have added to the group M.

berhautii and M. crotophora, species unknown to Braun, which have sporocarps attached in a row on the petiole by short peduncles, a strong transverse vein

intercepting the lateral veins of the sporocarp, and absence of a raphe and supe rior tooth on the sporocarp. All of the members of this species group, which I

have named Marsilea sect. Clemys, are tropical. The M. quadrifolia and M. diffusa groups (Fig. 1) both include species with

2-5 sporocarps per leaf and no vein anastomoses in the sporocarps, and are

distinguished from each other by the degree to which the peduncles are joined into a common trunk (well-developed trunk in the M. quadrifolia group). As I

discussed in the section Morphology and Anatomy, peduncle attachment can vary within populations, and thus seems to be a weak character on which to base such a distinction. I have therefore combined the two groups into a single section, sect.

Marsilea, which includes the species M. quadrifolia and M. minuta (an earlier name for M. er osa) found in the New World. Species of this section have sporo

carp attachment that is variable, a relatively small sporocarp with a raphe and

superior tooth, and internodal roots.

Braun placed M. macropoda in the M. quadrifolia group on the basis of its

tendency to have peduncles joined into a common trunk. However, the species shares many more similarities with members of Braun's M. mucronata group, such as presence of roots only at the nodes, synthesis of C-glycosylxanthones, the

presence of a multiseriate sporocarp epidermis, and large sporocarps with large numbers of sori. I also found presence of roots only at nodes and large sporocarps to occur in all of the members of the M. mutica group except M. mutica (M.

mutica has been shown to be conspecific with M. brownii of sect. Marsilea and is an earlier name). I therefore created sect. Nodorhizae in order to recognize that

these elements seem to form a monophyletic line. The section consists of New World species that inhabit dry and temperate habitats.

Within sect. Nodorhizae, it is possible to suggest character polarities but

difficult to distinguish between shared derivation and multiple parallelisms. For

example, the absence of a superior tooth on the sporocarps of M. ancylopoda, M.

macropoda, M. mollis, and M. oligospora is probably a derived feature, but I cannot discern how many times this character state evolved among these taxa.

Marsilea ancylopoda is unique among New World species of Marsilea, how

ever, for its sporocarp-burying habit, a character shared with three African

species, M. vera, M. distorta, and M. subterr?nea. Detailed comparison of these

species with M. ancylopoda will be necessary in order to determine whether these four species share the character through common ancestry or through parallelism, and thus whether they all should be included in sect. Nodorhizae or M. ancylo

poda taken out of it.




Better understanding of Marsilea phylogeny will require evaluation of the

remainder of Braun's species groups in this way. This has been hampered by the revision of Marsilea on a geographic basis. Although the present study is geo

graphic in circumscription as well, it is hoped that the preliminary infrageneric classification proposed here will direct revisionary work toward natural groups within the genus. In doing so it will be important to appreciate character diversity within the genus Marsilea as a whole, both for reconstructing the phylogeny of

species in the genus, and in order to make meaningful phylogenetic comparisons among Marsilea, Regnellidium, and Pilularia. For example, Schmidt (1978) placed

Regnellidium phylogenetically apart from Marsilea and Pilularia on the basis of its

internodal roots. As I have already discussed, root position is useful systemati

cally within Marsilea rather than between Marsilea and the other genera; Schmidt's conclusion was based upon examination of an insufficient sampling of

Marsilea.

Bower (1926) regarded Regnellidium, with two leaflets, as an evolutionary intermediate between Marsilea (four leaflets) and Pilularia (no leaflets). The studies of Schmidt (1978) and Wallace et al. (1984) have been valuable in examin

ing this hypothesis in light of new evidence, and I agree with these authors that

supporting evidence for Bower's hypothesis is lacking. In production of latex,

irregular sporocarp dehiscence mechanism, and nearly open dichotomous leaf

venation, Regnellidium does not make a good intermediate between the other two

genera. Pilularia, on the other hand, might well be considered a highly reduced

evolutionary offshoot of Marsilea, most closely allied with sect. Nodorhizae, as its

species lack internodal roots and have buried sporocarps much like those of M.

ancylopoda.

Relationship of the Marsileaceae to other Pteridophytes. Hypotheses concern

ing the closest relatives of the Marsileaceae have come largely from comparative

morphological studies of ferns, such as those of Campbell (1904), Bower (1926), and Bierhorst (1971). More recently, chromosome and chemical data have been used to augment such hypotheses (e.g., Wallace et al. 1984). In view of the

systematic findings presented here, it seems worthwhile to describe and evaluate three hypotheses.

A relationship of the Marsileaceae to the Schizaeaceae s. 1. was first sug

gested by Campbell (1904) and elaborated upon by Bower (1926). Bower sup

ported the hypothesis with nine pieces of evidence: 1) Creeping rhizomes are

shared by the Marsileaceae and Anemia subg. Anemiorrhiza (Smith) Prantl. 2) A solenostele and undivided leaf trace are shared by the Marsileaceae and Anemia subg. Anemiorrhiza. 3) Marsilea and Actinostachys pennula Hooker have dichotomously branched laminae. 4) Leaflet venation in Marsilea and Ane

mia Swartz is basically dichotomous. 5) Pilularia has filiform leaves like the sterile leaves of Schizaea pusilla Pursh. 6) The Marsileaceae and the Schizaea ceae have simple hairs rather than scales. 7) The Marsilea sporocarp can be

interpreted as a fertile pinna of Schizaea Smith that has been folded and fused.

8) Pilularia appears to have a vestigial annulus like the apical annulus found in Schizaeaceae. 9) Schizaea rupestris R. Brown [also 5. pusilla and S. robusta

Baker] often grows in wet places.

Many of these similarities are widespread among ferns in general, and thus




likely to represent parallelisms. Creeping rhizomes occur in a variety of both

primitive and derived terrestrial ferns, for example in Gleichenia Smith, Lygo dium Swartz, Pteridium Gleditsch ex Scopoli, Onoclea Linnaeus, Davallia Smith,

Woodwardia Smith, and Adiantum Linnaeus. Similarly, solenosteles occur in

many ferns with creeping rhizomes, such as Dennstaedtia Bernhardi and Lox soma R. Brown ex A. Cunningham. The characterization of leaf venation in

Marsilea and Anemia is not completely accurate; Marsilea leaflets have a well

developed vein reticulum, equalled in Anemia only by highly derivative species such as Anemia phyllitidis (Linnaeus) Swartz. The comparison of simple hairs in

the two families overlooks the peculiar hairs of Marsileaceae, with their trans

verse attachment totally unlike anything in the Schizaeaceae. I consider the leaf

of Pilularia to be a phyllodial, highly derived structure representing evolutionary reduction in response to growth underwater; it would thus not be a character

likely to be shared with an outgroup. Finally, many unrelated ferns, such as

species of Acrostichum Linnaeus, Thelypteris Schmidel, Onoclea, Ceratopteris, Salvinia Seguier, Azolla Lamarck, and Trichomanes Linnaeus, inhabit wet

places.

A more recent hypothesis suggests a relationship between the Hymenophylla ceae and Marsileaceae (Gupta 1962; Wallace et al. 1984). The evidence for this

hypothesis is as follows: 1) The development of the sorus is gradate in both

families. 2) Endosporic development of gametophytes occurs in some species of

Mecodium Presl ex Copeland. 3) The sori in both families are at the ends of veins.

4) The C-glycosylxanthones mangiferin and isomangiferin are produced by Car

diomanes reniforme Presl, some species of Mecodium, and by several species of

Marsilea. 5) The sporangia are borne on an elongate receptacle in both families.

6) The marsileaceous sporocarp can be considered to be derived from hymeno

phyllaceous indusia.

These data appear less superficial than those supporting the preceding hy

pothesis, but again there is reason to doubt the importance of many of them as true

indicators of relationship. The genus Mecodium appears twice in the above list, but

it is a relatively specialized genus in the Hymenophyllaceae (Copeland 1947) un

likely to exhibit so many ancestral family characters. The species of Marsilea that

produce C-glycosylxanthones are likewise relatively derived. Furthermore, Rich

ardson (1984), in a survey of the occurrence of C-glycosylxanthones in ferns,

argued that they occurred too widely among leptosporangiate ferns to be valuable as phylogenetic markers at the interfamiliar level. Some of the characters compared in the above list are not homologous; the elongate sori in Hymenophyllaceae are

the product of attachment of the sporangia to an elongate receptacle, but in Marsi

leaceae the elongate sori are the result of lateral expansion of a short-stalked, branched receptacle.

Hymenophyllaceae have two other superficial similarities to Marsileaceae that should be noted. Transversely-attached hairs similar to those of Marsileaceae occur in the hymenophyllaceous genera Mecodium and Meringium Presl and per

haps others. The laterally attached hairs of Mecodium and Meringium are at

tached by a stalklike extension of the basal transverse cell, however, not by a

stalk composed of one or two small cells as in Marsileaceae. Some species of

Trichomanes have regular nodal branching, as in Marsileaceae; H?bant-Mauri




(1972) showed, however, that trace divergence of the lateral shoot in Trichomanes

radicans Swartz could occur either from the main rhizome or from the petiolar trace. The latter is not known to occur in Marsileaceae.

These two hypotheses compare the Marsileaceae to extant fern groups. Meeuse (1961) suggested that the Marsileaceae shared a common ancestor with

the Mesozoic glossopterid seed ferns. Meeuse's hypothesis depended primarily upon a report of bisporangiate fertile structures in a species of Glossopteris

Brongniart. When Schopf (1976) dismissed the evidence for bisporangiate fertile

structures in Glossopteris as insufficient, Meeuse's hypothesis collapsed. This hy

pothesis is valuable, however, in directing attention toward considering fossil

groups in suggesting possible affinities of the Marsileaceae.

Review of fern fossils from the mid- to late Mesozoic might provide support for statements concerning homologies that are now based on conjecture. For

example, Ogura (1972) envisioned the petiolar vascular trace of Lygodium and

Schizaea as being derived from a Marsilea-type trace. This hypothesis would be

supported by the discovery of petiole fossils of intermediate morphology. The fossil record of the Marsileaceae is incomplete (Stewart 1983), and com

prises both megafossils and microfossils. Andrews and Boureau (1970) listed four

megafossil genera of Marsileaceae known from the mid-Mesozoic into the mid

Tertiary: Hydropterangium Halle, Rodeites Sahni, Marsilea, and Pilularia. More

recently, Fedotov (1978) reported Regnellidium from Eocene strata. Microfossils

of the extant genera Marsilea, Regnellidium, and Pilularia are known from Ter

tiary sediments (Dorofeev 1981), and the megaspore genera Arcellites Miner,

Molaspora Schemel, and Balmeisporites Cookson & Dettmann are known from

the Cretaceous (Hall 1963).

Hydropterangium, which was described from Triassic/Jurassic deposits in

Sweden (Halle 1910), is a sporocarplike capsule on a short stalk. Lundblad

(1950), who studied additional material of the genus in detail, considered it to

represent cupules of a member of the pteridosperm family Corystospermaceae. On this basis I will exclude it from further discussion of the family. About twelve

species of Marsilea and Pilularia have been reported from Cretaceous and Terti

ary deposits (Reed 1954, 1965) but need to be reevaluated, as most have not been

reinvestigated since their original description. In one of the few cases of such

reinvestigation, the Tertiary Marsilea bendirei Ward was transferred to Hydrangea Linnaeus (Knowlton 1902).

The fossil genus Rodeites, described from the Upper Cretaceous/Paleocene of India (Sahni 1943; Chitaley & Paradkar 1971, 1972), shares a number of

characteristics with species of Marsilea sect. Clemys. Although Rodeites was a

considerably larger plant than extant species of Marsilea, about twice as large as

robust specimens of M. crotophora, I found that it matches members of sect.

Clemys in shape of the petiolar vascular trace and attachment of several (at least

five) sporocarps to the petiole by short unbranched peduncles. Should additional

material of this genus also resemble these extant species of Marsilea, I suggest that Rodeites be placed in synonymy under Marsilea. This fossil demonstrates that character states present in sect. Clemys of Marsilea had arisen by the close of the Mesozoic Era.

The megaspores of Marsilea, Regnellidium, and Pilularia described by Doro




feev (1981) from the Eocene and Miocene of Siberia are indistinguishable from

those of extant species. The Cretaceous megaspore genera Arcellites, Molaspora, and Balmeisporites, however, differ markedly from the megaspores of extant

genera in ornamentation. All three are globose to ovoid and bear a tuft of spirally twisted appendages, the shortest of which occurs in Molaspora; wall sculpture in

Arcellites is baculate, in Molaspora granulate, and in Balmeisporites reticulate.

Spore walls in extant genera are smooth or indistinctly granulate. These mega

spores are locally common, particularly those of Arcellites, in both Lower and

Upper Cretaceous deposits in North America, Greenland, England, and Australia

(Hall 1963; Ellis & Tschudy 1964). The abundance of unabraded Arcellites megaspores in a paludal depositional

environment led Hall (1963) to conclude that the megaspores were produced by

plants growing in the swamp habitat and not by terrestrial or river plants whose

megaspores had been washed down into the depositional basin. Fossil sporocarps associated with these microfossils either have not been found or have been mis

identified as fossil seeds; similarly, leaf or rhizome remains of plants producing these spores are unknown.

Evolution of the sporocarp remains a subject for speculation. Eames (1936)

suggested that the sporocarp evolved as a means of protecting the spores during

dry periods. Although the completely closed, hard-walled sporocarps of present

day Marsileaceae function well to prevent desiccation and allow endozoic trans

port of the spores, it is difficult to envision evolutionary intermediates between the sporocarp and a sporiferous lamina as being capable of providing these func

tions. Perhaps the sporocarp served another function during its intermediate evo

lutionary stages. A possible explanation is that the sporocarp originally evolved as

a structure that promoted fertilization by keeping megaspores and microspores in

close proximity. Such a structure would not have had to be exceedingly thick

walled or completely enclosed, and would have been functional either on land or

in water.

Phylogenetic work on the Marsileaceae should have two immediate goals. First, infrageneric classification of Marsilea should be completed, so that addi tional taxonomic work on the genus is focused upon character-defined groups rather than geographic ones. Recognition of character trends in Marsilea arising from such reclassification will help in identifying characters that are most useful in

reconstructing intergeneric relationships. The second goal should be to develop as

complete a picture as possible of early marsileaceous plants. This will come

largely from study of fossil material and offers greatest promise in allowing new

hypotheses to be advanced concerning the relationship of the Marsileaceae to

other ferns.

TAXONOMY

In the lists of cited specimens, the letters "f "

(fertile) and "st" (sterile) follow the citation of herbaria housing the collection. An "f" or "st" at the end of a list of herbaria, preceded by a semicolon, applies to all the duplicates. If the condi tion is variable among duplicates of a particular collection, "f

" or "st" is given for

each specimen.




Marsilea Linnaeus, Sp. pi. 2: 1099. 1753.?Type: Marsilea quadrifolia Linnaeus

(lectotype by convention; action of Necker requires that it be conserved). Lemma Jussieu ex Adanson, Fam. 2: 21. 1763.?Type: Lemma quadrifolia

(Linnaeus) Desrousseaux in Lamarck & Poiret, Encycl. 3: 720. 1792.

Zaluzianskia Necker, Hist. & Comment?t. Acad. Elect. Sei. Theodor.-Palat.

3: 303. 1775, non Zaluzianskya F. W. Schmidt, 1793.?Type: Zaluzian

skia marsiloides Necker [=Marsilea quadrifolia Linnaeus].

Low rhizomatous aquatic or amphibious herbs, forming diffuse or dense colo

nies; usually rooted, entire plant floating in some species. Rhizome monopodial, with lateral shoots arising at nodes and often very much condensed so that the

leaves appear clustered. Roots adventitious, threadlike, pinnately branched, pre sent only at the nodes in some species and also on the internodes in others.

Leaves distichous; petioles slender, upright or decumbent, bearing at the apex two pairs of cun?ate leaflets that are pulvinate at the base; leaflets dichotomously veined, the veins anastomosing regularly to form a reticulum of elongate ar?oles;

hydropoten in the form of red or brown streaks commonly occurring on the

abaxial intercostal epidermis of leaflets of floating leaves; lateral margins of leaf

let concave, straight, or convex, terminal margin of leaflet entire (rarely remotely denticulate or crenate in New World species). Rhizomes, leaves, and sporocarps covered to varying degrees with 2-9-celled trichomes, the basal cell transversely attached to a 1-2-celled stalk; outer surfaces of trichome cells often verrucose.

Fertile leaves usually terrestrial, rarely submersed, borne on both short and long shoots, with branched or unbranched peduncles bearing hardened globoid or

discoid sporocarps at the tips and diverging from the petiole at or above its base.

Sporocarps attached laterally or terminally to the peduncle apex, which may be

adnate for a short distance to the sporocarp (the raphe), often ending in a blunt

tooth, in some species with a second tooth superior to it on the sporocarp;

sporocarp walls pinnately veined within, the secondary veins branching and anas

tomosing to varying degrees. Sori enclosed in the sporocarp, disposed in two

rows, sausage-shaped, borne on a short-stalked receptacle that is transversely dilated and occasionally branched, with microsporangia borne along the margins of the sorus and the megasporangia borne medially; sori attached by a thin medial

membrane to a cellular gelatinous elongate mass (sorophore) that is either free at

the tip or formed into a ring. Sporangia all clear-walled and without annuli.

Microspores 16-64 per sporangium, white or pale brown, bearing trilete laesurae,

granulate, indistinctly reticulate, cristate, or smooth; microspores occasionally abortive, and then either smaller and brown, or larger, globose, and thin-walled.

Megaspores one per sporangium, ovoid, white, with a hemispherical or oblong

papilla at one end, surface smooth or indistinctly reticulate.

Key to Species, Subspecies, and Putative Hybrids of Marsilea in the New World

1. Rhizomes bearing roots at nodes and also 1-3 on internodes.

2. Sporocarp lacking a raphe and superior tooth (Fig. 7b). 3. Sporocarps 1-4, on proximal Va of the petiole.




4. Sporocarp 3.5-6.0 mm long, angled in cross section, with conspicuous lateral ribs.

3. M. deflexa. 4. Sporocarp 2.7-3.1 mm long, nearly terete, lateral ribs indistinct or absent.

3. x 4. M. deflexa x polycarpa. 3. Sporocarps 3-25, on proximal Vh of the petiole.

5. Sporocarp less than 3 mm long, terete. 4. M. polycarpa. 5. Sporocarp 3.1-3.9 mm long, slightly angled or ovate in cross section.

6. Peduncles sharply deflexed; sporocarps 4-11 per petiole, usually not overlapping. 3. x 5. M. x subangulata.

6. Peduncles curved, hooklike; sporocarps 5-20 per petiole, usually crowded and

overlapping. 5. M. crotophora. 2. Sporocarp with a raphe; superior tooth present or absent (Fig. 7a).

7. Peduncle recurved or prostrate, often hooked again at the base of the raphe (Fig. 15);

sporocarp underground or below rhizome level, usually lacking a superior tooth.

6. M. ancylopoda. 7. Peduncle erect or slightly decumbent, never hooked at the base of the raphe; sporo

carp above ground or rhizome level, with a superior tooth present or absent.

8. Sporocarp nodding on peduncle; leaves pilose. 8. M. mollis.

8. Sporocarp perpendicular or slightly ascending on peduncle; leaves glabrous or with

a few short appressed hairs.

9. Sporocarp 4.0-5.6 mm long, 2.3-2.8 mm thick; peduncle often branched, with

1-3 sporocarps per leaf. 1. M. quadrifolia. 9. Sporocarp 2.6-4.1 mm long, less than 2.0 mm thick; peduncle branched or

unbranched, with 1-4 sporocarps per leaf. 2. M. minuta.

1. Rhizomes bearing roots only at the nodes.

10. Superior tooth of sporocarp (0.2-) 0.4-1.2 mm long, acute.

11. Abaxial surface of leaflet covered with overlapping hairs.

12. Both lateral margins of leaflet straight or convex; Hawaii. 12. M. villosa.

12. One or both lateral margins of leaflet concave; North America.

13. Hairs of leaflet appressed, the abaxial ones not extending beyond leaflet

margin to make leaflet appear white-bordered adaxially. 10a. M. vestita subsp. vestita.

13. Hairs of leaflet with spreading tips, the abaxial ones extending beyond the

leaflet margin to make leaflet appear white-margined adaxially. 9. x 10. M. macropoda x vestita.

11. Leaflets with sparse appressed hairs, or glabrate abaxially. 14. Leaflets twice as long as wide or longer.

15. Sporocarp strongly nodding; Caribbean. 11. M. nashii.

15. Sporocarp slightly nodding to strongly ascending; central Texas.

10b. M. vestita subsp. tenuifolia. 14. Leaflets less than twice as long as wide.

16. Sporocarps nodding, trichome scars not conspicuous; Caribbean. 11. M. nashii.

16. Sporocarps slightly nodding to slightly ascending, usually with conspicuous trichome scars; North America. 10a. M. vestita subsp. vestita.

10. Superior tooth of sporocarp up to 0.4 mm long, blunt, or absent.

17. Sporocarp 6-9 mm long, strongly ascending; peduncles usually branched.

9. M. macropoda. 17. Sporocarp 2.4-6.0 mm long, perpendicular to strongly nodding; peduncles

unbranched.

18. Peduncle recurved or prostrate, often hooked again at the base of the raphe

(Fig. 15e); sporocarp underground or below rhizome level. 6. M. ancylopoda. 18. Peduncle erect, never hooked at the base of the raphe; sporocarp above ground

or rhizome level.

19. Sporocarp 2-3 mm wide, inferior tooth of sporocarp 0.2 mm long, blunt

and straight, or absent (Fig. 171); high elevations from Arizona and western

Texas to northern Argentina. 8. M. mollis.




19. Sporocarp 3.6-4 mm wide, with the inferior tooth 0.2-0.6 mm long and

curved away from the sporocarp (Fig. 17k); northwestern U.S.A.

7. M. oligospora.

I. Marsilea section Marsilea.

Plants with both nodal and internodal roots, and usually with nodal shoots not

condensed or else bearing only 1-2 leaves. Sporocarps 1-4, 2.6-5.6 mm long (in New World species), attached to the petiole above the base on branched or

unbranched peduncles; raphe present, inferior tooth poorly developed, superior tooth well developed or absent; lateral veins of sporocarp not intercepted by a

transverse vein. Sori 9-17.

1. Marsilea quadrifolia Linnaeus, Sp. pi. 2: 1099. 1753. Zaluzianskia marsiloides

Necker, Hist. & Comment?t. Acad. Elect. Sei. Theodor.-Palat. 3: 303.

1775. Lemma quadrifolia (Linnaeus) Desrousseaux in Lamarck & Poiret,

Encycl. 3: 720. 1792. Zaluzianskia quadrifolia (Linnaeus) Kuntze, Revis,

gen. pi. 2: 823.1891.?Type: [France?] 1717, A deJussieus.n. (lectotype, here designated: specimen 1599-A, P-JU, IDC=microfiche 6206-4: 102).

Plants forming diffuse colonies. Rhizome 0.5-1.3 mm thick, reddish brown to

black, sparsely hairy to glabrate, bearing short nodal shoots, nodal and internodal roots 0.2-0.3 mm thick, internodes 0.6-5 cm long; rhizome in water 0.9-2.0 mm

thick, green, glabrous, aerenchymatous, internodes 4-12 cm long. Land leaves

with terete petioles 5.4-16.5 cm long, 0.5-1.0 mm thick, leaflets 0.7-2.1 cm long, 0.6-1.9 cm wide, symmetrical, flabellate, glabrous or with a few non-overlapping hairs; floating leaves with terete petioles 14-30 cm long, 1.0-1.5 mm thick, leaf lets 1.3-3 cm long, 1.2-3.1 cm wide; hydropoten irregularly distributed or absent.

Fertile leaves produced on land (rarely in water) on long shoots or short shoots,

bearing 1-3 sporocarps on a branched or unbranched peduncle attached 1-12 mm

above petiole base; unbranched peduncle or ultimate branches of peduncle 3-16 mm long, common trunk of branched peduncle 1-4 mm long (rarely 2-3 un

branched peduncles attached separately to the same petiole). Sporocarps 4.0-5.6 mm long, 3.1-4.0 mm wide, 2.3-2.8 mm thick, rounded, oval, or elliptical in

lateral view, elliptical to nearly round in cross section, dark brown to black, hairy but soon glabrate; raphe 1.4-1.9 mm long, inferior tooth usually absent, superior tooth absent or 0.1-0.2 mm long, acute; sporocarp veins ca 20, forking halfway from median vein, the branches anastomosing just before the tips or free. Sori 10-17 per sporocarp, borne on a sorophore with a free, acute tip, ca 12 micro

sporangia and 3-7 megasporangia per sorus; microspores ca 43 per sporangium, 56-61 |xm in diameter; megaspores 560-610 |xm long, 355 [xm wide, with an

apical papilla 60 |xm long. Figs. 4h, 5n, lle-g. Phenology. Produces sporocarps from mid-June to mid-October in North

America. Plants from Michigan that were cultivated in the greenhouse died back to the rhizome in November-December and sprouted the following February

March for two consecutive years. Plants in the field in Michigan were observed

sprouting from old rhizomes in mid-April.




FIG. 11. Morphology of Marsilea minuta and M. quadrifolia. M. minuta: a. leaf; b. crenate

leaflet; c. sporocarps; d. variation in attachment of sporocarps. M. quadrifolia: e. leaf; f. sporocarps;

g. variation in attachment of sporocarps. (Scale: short bar-a, b, e; long bar-c, f.)

Distribution. In North America Marsilea quadrifolia is found in ponds, river

backwaters, and marshes, where it occurs from the shores out to a depth of ca 0.5 m. Specimens collected by Hellquist in Massachusetts were from water with

slightly below neutral pH and low alkalinity, while plants near Ann Arbor, Michi

gan, thrive in water with both high pH and alkalinity. Marsilea quadrifolia was first collected in North America from Bantam Lake

near Litchfield, Connecticut, by T. F. Allen and D. C. Eaton in 1860. Although its subsequent appearance at new localities in northeastern North America is well

documented by herbarium specimens, in but few cases was the origin of a new

colony known. In New England, some new localities were the result of deliberate

introductions; around 1868, plants were brought from Bantam Lake to the Bo

tanical Garden in Cambridge, Massachusetts, and transplants were made from

there to Fresh Pond in Cambridge and to Concord, Massachusetts. Plants were

introduced directly from Bantam Lake to Cromwell, Connecticut, and to Salem

and Maiden, Massachusetts. It is also likely that the species was introduced as a

botanical subject or curiosity near universities such as Yale, Cornell, and the

University of Massachusetts. Gier (1955) thought that M. quadrifolia was perhaps introduced into a fish hatchery pond in Platte County, Missouri, along with

aquatic plantings. The New Jersey specimen was from near the establishment of a




tropical fish supplier and probably represents a temporary escape; the plant could

not be relocated in August 1982. Spread of M. quadrifolia in North America is

summarized in Fig. 12.

In addition to this evidence for deliberate or accidental dispersal of M. quad

rifolia by man, it seems probable that some North American stations are the

result of introduction by birds or dispersal by flowing water, and that the species will continue to increase in abundance and appear in new localities in the future.

Unlike many species of Marsilea, M. quadrifolia is capable of persisting for long

periods of time in the same locality; it was collected from Bantam Lake as re

cently as 1974 and has persisted in Illinois for 35 years (Henry 1983) and in

Washtenaw County, Michigan, for 23 years. Marsilea quadrifolia competes well

with native aquatics, as described by Henry (1983) and Burk et al. (1976), al

though the latter pointed out that it did not spread down a creek into a nearby marsh until after the marsh had been disturbed through dredging.

Representative Specimens. Canada. Ontario: Haldimand Co., Nanticoke Creek Vi mi SW of

Nanticoke, Miller 647 (NY, UC, US; st). Peel Co., Mississauga, Lome Park N of CNR, just W of

Lornewood Creek, Webber & Kaiser 4787(5) (MICH st).?U.S.A. Connecticut: Fairfield Co., strand

of Poquonock R., Seymour 20230 (MO f). Litchfield Co., Bantam Lake, Litchfield, Aug 1860, Allen

s.n. (GH f); Sep 1860, Allen s.n. (F f); Dwyer 2111 (NY f); Sep 1860, Eaton s.n. (F, GH, MO, NY,

PH; f); Schuyler 4501 (PH st). Middlesex Co., Cromwell, Harger 6817 (PH, UC; st). New Haven Co.,

Southbury, pond adjoining Lake Zoar in the Housatonic River, 26 Aug 1929, Eames s.n. (MO f); Lake Whitney, New Haven, 3 Oct 1883, Setchells.n. (UC f). Illinois: Vermilion Co., Kickapoo State

Park near Danville, Jones & Jones 46493 (NLU f); E of Oakwood, Lane 222 (F f). Indiana: Clark

Co., Cooley's Pond VA mi S of Bordens on Rt Ind 60, Reed 52412 (US f). Iowa: Van Buren Co.,

Lacey-Keosauqua State Park, Davidson et al. 1821 (TEX f). Kentucky: Casey Co., Liberty, Johnson

682 (MICH f). Fayette Co., 3 mi E of Lexington, 1920, McFarland s.n. (US f); 2 mi E of Lexington

along the C & O RR, McFarland 46 (CAS, MICH, MO, NY, PH, UC, WS; f). Maine: Somerset Co., Coburn Park, Skowhegan, Fassen 13562 (F st). Maryland: Anne Arundel Co., Wagner's Pond, Glen

Burnie, Fessenden 5592 (US f); Glen Burnie, 5 Oct 1909, Shreve s.n. (PH f). Baltimore City Co.,

Baltimore, Lotsy s.n. (US f). Wicomico Co., W side of Salisbury, 16 Jun 1949, Uhler & Zellers.n. (US

f). Massachusetts: Barnstable Co., near Nobska Point [Woods Hole], 30 Aug 1910, Brooks s.n. (UC

f); 10 Aug 1928, Faull s.n. (F, GH, MO, US; st). Berkshire Co., Great Barrington, 3 Aug 1923,

Ferguson s.n. (NY st). Boxford Co., Stevens Pond, Boxford, Blake 7184 (TEX f). Essex Co., Salem, 19 Jul 1895, E. T. Harper herb. (F, UC; st); Spofford's Pond, Boxford, Oct 1900, Horner s.n. (NY f).

Hampshire Co., Amherst, Fosberg 44302 (US f). Middlesex Co., Cambridge, Bot. Garden, Aug 1868, Porter s.n. (CM, F; f); Fresh Pond, Cambridge, Sep 1873, Davenport s.n. (NY f); Maiden, 11 Jul

1877, Morongs.n. (NY f); Belmont, 23 Aug 1881, Manning s.n. (NY f); Cambridge, Glacialis Pond, 5

Oct 1887, Sturgis s.n. (NY f); Concord River, Concord, Underwood 2911 (NY st); Concord River,

Billerica, 28 Sep 1901, Knowlton s.n. (GH f); Sudbury River, Concord, 21 Aug 1904, Worthen s.n.

(US f ); Sudbury River along Central Street S of Mass. Pike, Framingham, Hellquist 10934 (ASU, MO,

NLU; st). Norfolk Co., Charles River, Dedham, 15 Sep 1894, Kennedy s.n. (GH, PH; f); Rt 6 at town

line [Wellesley] with Newton Upper Falls, Brown 2242 (TEX st). Suffolk Co., Forest Hills, Arnold

Arboretum, 19 Jul 1890, Merrow s.n. (MICH f ); Charles River, W Roxbury, 20 Aug 1902, Forbes s.n.

(PH f); Arnold Arboretum, Palmer 46540 (MO, PH; f). Worcester Co., Fitchburg RR, Ice RR, 26 Jul

1877, Boon herb. (GH f). Michigan: Washtenaw Co., S side of Huron River ca 2.5 mi NW of Ann

Arbor, Voss 10719 (MICH st); Murray & Johnson 1467 (MICH st). Missouri: Barton Co., NW corner

NE Va NE Vi Sect 19-33-29W, 29 Sep 1961, Dunlap s.n. (NLU f, SMS st); 1 mi NE of Milford, Palmer

53949 (GH, KANU; st); Palmer 54495 (MICH f). Boone Co., Watkins Pond SW of Midway, 12 Jun

1963, Dunlap s.n. (SMS st). Platte Co., Basswood Lakes, Platte City, 11 Oct 1953, Gier s.n. (F f). New Jersey: Morris Co., between Morristown and Florham Park near Ely's Water Garden, True 413

(PH st). New York: Bronx Co., New York Botanical Garden, Bronx, Sep 1906, Shafer s.n. (CM f). Suffolk Co., Cold Spring Harbor, 4th Lake, 24 Jul 1915, Kirch s.n. (CM st). Tompkins Co., Lake

wood, Cayuga Lake, 27 Jul 1915, Bright s.n. (CM st); Ithaca, Eddy Pond, Cascadilla Creek, 27 Aug




FIG. 12. Distribution of Marsilea quadrifolia in northeastern North America. Numbers refer to

intervals in years during which specimens were first collected at a locality: 1. 1840-1860; 2. 1861-1880; 3. 1881-1900; 4. 1901-1920; 5. 1921-1940; 6. 1941-1960; 7. 1961-1980; 8. 1981-present.

1893, J. Schrenk herb. (MO f). Ohio: Fairfield Co., S of Lancaster, Rt 33 behind Crawford Pumping

Station, 21 Aug 1958, Henry & Baker s.n. (CM f); Ashkeena Nature Preserve S of Lancaster, Roberts

907 (MICH st). Pennsylvania: Delaware Co., Crum Lynne, 16 Jun 1894, Leeds & Leeds s.n. (PH f); near Media, 28 Oct 1923, Trudell s.n. (US st); Vi mi NE of Wallingford, 8 Sep 1945, Wherry s.n. (PH

f); Ridley Creek N of Hwy W of Media, 20 Jul 1971, Wherry s.n. (PH f). Monroe Co., S of

Stroudsburg, LaBar's Rhododendron Nursery, 9 Sep 1941, Harmon s.n. (PH f).

Marsilea quadrifolia and M. macropoda (no. 9) are the only temperate North

American species of Marsilea that bear sporocarps on branched peduncles. Marsi

lea quadrifolia is virtually glabrous and bears sporocarps 4.0-5.6 mm long, while

M. macropoda is hairy and has sporocarps 6-9 mm long. Internodal roots and the more symmetrical leaflets may be used to distinguish M. quadrifolia from atypical

specimens of M. vestita (no. 10) (Johnson 1985a). Although they do not overlap in range in the Western Hemisphere, M. quadrifolia can be confused with M.

minuta (no. 2). The latter has, however, a slightly smaller sporocarp with a more

conspicuous superior tooth and shorter peduncles than M. quadrifolia. Braun (1871) placed M. quadrifolia in a "section" of Marsilea with M. ma

cropoda and M. brownii A. Braun (now included in M. mutica) on the basis of

the branched peduncle. Although I exclude M. macropoda (no. 9) from the group on the basis of its sharing other characters with North American species, I con

tinue to recognize the group and add to it M. minuta and its close relatives in the

Old World.

A lectotype for M. quadrifolia had never been chosen. The Linnaean phrase name "Marsilea foliis quaternatis" distinguishes M. quadrifolia from the other




Linnaean species of Marsilea, M. (now Salvinia) natans, but is not helpful as a

guide in choosing a lectotype. A specimen in the Jussieu herbarium, collected by A. de Jussieu in 1717 and thus probably seen by Linnaeus in his visit to Paris, makes a suitable lectotype and serves the interests of nomenclatural stability.

2. Marsilea minuta Linnaeus, Mant. pi. 308. 1771, non M. minuta E. Fournier, 1880.?Type: India. Savage Catalog 1254.6 (LINN, fide Launert 1968).

Synonyms for this species are listed by Gupta (1962) and Launert (1968).

Plants forming extensive but diffuse colonies. Rhizome 0.4-0.8 mm thick,

green to light brown, densely covered with tan hairs at apices but glabrate proxi

mally, sometimes bearing short branches with numerous leaves at nodes, nodal and

internodal roots 0.1-0.3 mm thick, internodes 1-3.5 cm long; rhizome in water

0.5-0.8 mm thick, green to brown, glabrous, internodes 4-11 cm long. Land leaves

with erect terete petioles 5-13 cm long, 0.4-0.8 mm thick, leaflets 1.2-2 cm long, 0.8-1.7 cm wide, cun?ate to flabellate, glabrous to sparsely hairy, with concave,

straight, or convex lateral margins and entire to crenulate terminal margins; leaves

in water often with leaflets emergent rather than floating, with stiff terete petioles 13.5-47 cm long, 0.3-0.8 mm thick, leaflets 1.7-1.8 cm long, 1.5-1.6 cm wide;

hydropoten infrequent. Fertile leaves produced on land, bearing 1-4 sporocarps

per leaf, on either branched or unbranched peduncles attached at or slightly above

the base of the petiole, unbranched peduncles and ultimate divisions of branching

peduncles 2.6-6.0 mm long, the common trunk of branched peduncles 0.4 mm

long. Sporocarps 2.6-4.1 mm long, 2.4-3.1 mm wide, 1.3-1.7 mm thick, nearly round to slightly oblong in lateral view, ovate or elliptical in cross section, brown to

black, hairy to glabrate; raphe 1.5-2.2 mm long, inferior tooth 0.3-0.6 mm long, obtuse or truncate, or absent, superior tooth 0.3-0.6 mm long, acute; sporocarp veins ca 15, forking midway, branches often anastomosing at tips. Sori 9-12 per

sporocarp, attached to a sorophore with a free acute tip, 9-14 microsporangia and

2-7 megasporangia per sorus. Microspores 50-64 per sporangium, 50-75 |xm in

diameter, with 1-2 spores per sporangium occasionally brown, misshapen, up to 32

fxm long. Megaspores 400-525 jjum long, 355-380 |xm wide, with an apical papilla 40-65 jxm long. Figs. 2d, 4g, 5m, 8a, lla-d.

Phenology. Collections of fertile material have been made in March, June,

September, and November.

Distribution. (Fig. 16). In the New World, M. minuta is known only from

Trinidad, Tobago, and Pernambuco, Brazil, where it grows at low elevations near

the coast in fresh water or occasionally in brackish water (Trinidad) on sandy or

clay substrates. In eastern Trinidad this species has formed a colony that extends

for several kilometers in a coastal coconut strip, but it is also found in a nearby swamp as well. In northeastern Brazil the plants have been collected in seasonal

ponds. Marsilea minuta is a weedy, common, and widely distributed plant in

Africa and India; its rarity in the New World may indicate that it was introduced

only recently.

Representative Specimens. Trinidad. Nariva Swamp, Davison TR-12 (MO f); Nariva Cocal, Freeman 7946 (NY st, TRIN f, st); Nariva Cocal, 7.2 km S of point where Manzanilla-Mayaro Road

reaches Manzanilla Bay, Johnson 797 (MICH f ); Nariva Swamp, 12.7 km S of point where Manzanilla

Mayaro Road reaches Manzanilla Bay, Johnson 798 (MICH f); Kernaham, Nariva Swamp, Ramcha




ran 440 (BM, K, TRIN; f).?Tobago. Ca 5 mi SW of Roxborough, Mickel 9673 (MICH f).?Brazil. Pernambuco: Tapera, Pickel 3116 (CAS, M, MICH, RB; f ); pantano re Olinda, 4 Aug 1887, Ridley et

al. s.n. (BM f); Casa Caiada, Tavares 626 (US f); Paulista, Caminho para as ruinas da igreja de

Maranguape, Tavares 841 (US f). State unknown: Glaziou 5213 (P f).

Marsilea minuta is distinguished from all other New World marsileas by the

combination of the small sporocarp with a conspicuous raphe and superior tooth, the several sporocarps per petiole, and internodal roots.

This species is quite close to M. quadrifolia (no. 1), and in fact specimens of

Marsilea from China seem intermediate between the two species in sporocarp size

and peduncle attachment. Study of a wide range of Old World material of Marsi

lea would be required, however, to resolve the question of whether M. quadrifolia and M. minuta represent distinct species.

II. Marsilea section Clemys D. M. Johnson, sect. nov.?Type: Marsilea polycarpa Hooker & Greville.

Marsileae radicibus ad et inter nodos, surculis lateralibus condensatis vel non

condensatis, sporocarpibus 2.5-6.0 mm longis 1-25 in serie in petiolis pendunculis brevibus nonramosis portato, raphe, dente inferiore, et dente superiore sporocar

pii absentibus, nervis lateralibus sporocarpii vena transversis interceptis, et soris

4-14 intra sporocarpiam. Of the five species assigned to this section, three are neotropical, one (M.

berhautii) is African, and the fifth (undescribed) Malaysian. This section has the

circumscription of Braun's "Gruppe der M. polycarpa," except that M. subterr? nea A. Braun is excluded on the basis of its possession of a sporocarp raphe. The

section name is from Greek clemys, a tortoise or turtle, suggested by the common

name bora galapaguera, roughly translated as "turtle weed," for Marsilea in parts of Venezuela; it replaces the invalid sectional name Zalusianskaya given to the

group by Alderwerelt (1915).

3. Marsilea deflexa A. Braun, Monatsber. K?nigl. Preuss. Akad. Wiss. Berlin

1863: 421. 1864. Zaluzianskia deflexa (A. Braun) Kuntze, Revis, gen. pi. 2: 823. 1891.?Type: Brazil. Piaui, 1839, Gardner 2760 (holotype: G!;

isotypes: BM! G! K! P!). Marsilea striata Mettenius, Ann. Sei. Nat. Bot., s?r. 5, 3: 310. 1865.?Type:

Colombia. Aposentos, llano de Ibague, pro v. de Mariquita, 500 m, 1851

1857, Triana 691 (holotype: LZ, destroyed; isotypes: BM! COL! GH! P!).

Plants forming dense colonies. Rhizome 0.5-2.0 mm thick, green to brown,

densely covered with tan hairs at apices but glabrate proximally, nodal shoots usually

lacking compressed internodes and thus similar to main shoot, nodal and internodal roots 0.2-0.3 mm thick, internodes 1.5-6.5 cm long; rhizome in water 0.8-1.6 mm

thick, green, glabrous, internodes 1.6-4.8 cm long. Land leaves with procumbent to

erect terete glabrate petioles 2-9.3 cm long, 0.5-0.7 mm thick, leaflets 1.1-2 cm

long, 0.9-1.7 cm wide, obdeltate to flabellate, glabrous or sparsely hairy, with

concave, straight, or convex lateral margins and entire terminal margins; floating leaves with flexuous glabrous petioles 4.6-18 cm long, 0.7-1.2 mm thick, leaflets

1.5-3 cm long, 1.6-3 cm wide, obdeltate or flabellate, with straight or convex




margins; hydropoten usually present and uniformly distributed, except for a small

patch just distal to the pulvini. Fertile leaves produced both on land and in water,

bearing 1-4 sporocarps on the proximal lA of the petiole, the lowest attached 1-6 mm

above the petiole base on unbranched peduncles 1.5-4 mm long, 0.3-0.7 mm thick.

Sporocarps 3.5-6.0 mm long, 2.0-4.5 mm wide, 1.7-2.8 mm thick, rectangular,

quadrate, ovate, or trapezoidal in lateral view, with conspicuous lateral ribs, strongly

pentagonal in cross section, brown to purplish black, covered with flattened matted

hairs at first but eventually glabrate; raphe and teeth absent. Sori 11-14 per sporo

carp, attached to a sorophore that often forms a complete ring, 15-35 microsporan

gia and 2-7 megasporangia per sorus. Microspores 50-64 per sporangium, 55-75 jxm in diameter, 2-3 spores per sporangium occasionally brown, misshapen, and up to

35 |xm long. Megaspores 490-740 |xm long, 440-580 |xm wide, with an apical papilla 50-75 n,m long. Figs. 2h, i, 4i, 5j, 7b, 8b, 9d, 10a, 13e-h.

Phenology. Produces sporocarps throughout the year. No evidence has been

found that viable rhizomes persist through the dry seasons; the plants presumably

reproduce each wet season with the dehiscence of new sporocarps. Distribution. (Fig. 14). Marsilea deflexa is found from Nayarit and Veracruz

in central Mexico south through Central America into South America, where it

extends east to Piaui, Brazil, and south to Paraguay. M. deflexa occurs in seasonal

ponds, marshes, and ditches from near sea level up to 1100 m. All populations seen in the field were on clay substrates, and commonly grew with species of

Caperonia, Neptunia, Utricularia, and Najas, and often formed thick solid mats of

floating leaflets in shallow water. At one locality in northwestern Venezuela, this

species was found growing sympatrically with M. ancylopoda; no evidence of

hybridization was found, however. In fact, the two species seemed to be partition

ing the habitat, with M. deflexa occurring in the shallow water and on mud but

not persisting with drying of the mud surface, and M. ancylopoda growing on the

muddy edges and up into areas that were dry and somewhat grassy.

Specimens Examined. Mexico. Jalisco: 8 km al N de Cruz de Loreto sobre el camino a

Tomatl?n, Rzedowski & McVaugh 1331 (ENCB st). Nayarit: 2 mi SE of Las Varas, McVaugh 19287

(MICH f). Oaxaca: km 36 de la carretera Pinotepa-Acapulco, Lachica & S?nchez FaI-2118 (CAS,

ENCB, MEXU; st). Puebla: Huachinango, Mesa San Diego, Bravo H. 523 (MEXU st). Veracruz:

Mpio Xalapa, Rancho La Palma, congregaci?n de El Castillo, Ortega O. 0-583 (UC f).?Guatemala.

Chiquimula: valley of R?o Chiquimula, 1.5 mi NE of Chiquimula, Steyermark 30117 (F st). Peten: La

Libertad, Lundell 2579 (F, MICH; st); Sacluc, Bernoulli & Cario 145 (P st).?Honduras. Olancho:

entre San Pedro Catacamas y San Felipe, Molina R. 13266 (F f, LL f, NY st).?Costa Rica.

Guanacaste: a unos 45 km al NO de Liberia, Jim?nez M. 348 (CR, G; f ); 0.2 km W of Pan-American

Hwy on road to Cuajiniquil, Murray & Johnson 863 (MICH f); 0.3 km W of Pan-American Hwy on

side road between kms 257 and 258, 5.3 km N of bridge over R?o Ahogados, Murray & Johnson 868

(MICH f); Parque Hist?rico Santa Rosa, 3 Dec 1977, Poveda s.n. (CR f); about 5 km S of La Cruz,

Williams & Williams 24536 (LL, NY, US; f ).?Colombia. Tolima: Altamira above Tolima, Lehmann

8714 (G, GH, K, NY, S, US; f).?Venezuela. Apure: Dist. Mu?oz, Ca?o Caicara, 11 airline km W

of Mantecal gallery forest, Davidse & Gonz?lez 14783 (MO, UC, VEN; f); M?dulos F. Corrales de la

UNELLEZ, Mantecal, Stergios 2491 (PORT, UC; f); Hato "El Frio," Velasquez 842 (VEN f). Cojedes: "Limon," San Carlos, Rudd 367 (VEN f). Falc?n: 2 km E of Huequito, Johnson 778

(CORO, MICH, VEN; f). Gu?rico: cerca Hato Becerra, a unos 20 km de Calabozo, v?a Cazorla,

Aristeguieta 6463 (VEN f); km 239 of San Fernando-Calabozo highway, 36 km N of Camagu?n, Johnson 794 (MICH, VEN; f); Palo Seco, llanos de Calabozo, en ci?negas cerca de Misi?n Arriba,

Lasser 127 (US f, VEN f); San Juan de Los Morros, Pittier 10153 (G f, NY st, US f, VEN f); Calabozo, Velasquez 760 (VEN f).?Brazil. Terr. Roraima: Maruay, L?tzelburg 21187 (M, R, UC;

f). State unknown: Glaziou 16648 (C f, K f, P st).?Peru. San Mart?n: in einem T?mpel bei




FIG. 13. Morphology of Marsilea sect. Clemys. M. polycarpa: a. fertile leaves; b. floating plant; c. sporocarp. M. deflexa x polycarpa: d. sporocarp. M. deflexa: e. sporocarp; f. plant with floating

leaves; g. abaxial surface of floating leaf, showing hydropoten; h. land leaf with sporocarps. M. x

subangulata: i. sporocarp. M. crotophora: j. sporocarp; k. habit. (Scale: short bar-a, b, f, g, h, k; long

bar-c, d, e, i, j.)




FIG. 14. Distribution of the neotropical species and putative hybrids of Marsilea sect. Clemys: M.

crotophora, M. deflexa, M. polycarpa, M. xsubangulata (M. crotophora x deflexa), and M. deflexa x

polycarpa.

Moralles, Tarapoto, Ule 6866 (G st, K f, P f).?Paraguay. Alto Paraguay: Puerto Casado and

vicinity, Pedersen 4068 (C, G, GH, NY, P, S, US; f). Concepci?n: Concepci?n, Rojas 1834 (MO f, SI

st). Itapua: Trinidad, in uliginosis prope Escalava, Osten & Rojas 8689 (S f ).

When fertile, M. deflexa can be separated from all other species by its rela

tively large angular sporocarps with conspicuous lateral ribs. When sterile, how

ever, the species is virtually impossible to distinguish from other members of sect.

Clemys. Plants of M. deflexa are usually rooted to the substrate, even in fairly

deep water, while plants of M. polycarpa and M. crotophora usually have floating rhizomes. Marsilea deflexa seems to occur in slightly drier climates and at higher elevations than either of the other two species.

The closest relative of M. deflexa is the west African species M. berhautii, with which it shares the row of angular sporocarps on the petiole and the capacity for producing sporocarps while in water. Marsilea berhautii differs in the sporo

carps being less strongly angled and in having 8-12, rather than 1-4, sporocarps

per leaf.

The epithet deflexa refers to the sporocarp peduncles of this species, which are folded back against the petiole on which they are borne. The epithet striata

was in recognition of the hydropoten, which were presumably as conspicuous in

the holotype as they are in the isotypes.




4. Marsilea polycarpa Hooker & Greville, Icon, filie. 2: t. 160. 1830. Zaluzianskia

polycarpa (Hooker & Greville) Kuntze, Revis, gen. pl. 2: 823. 1891.?

Type: Guyana. Demerara, Parker s.n. (lectotype, here designated: K!;

isolectotype: K!). Marsilea brasiliensis Martius, Icon. pl. crypt. 4: t. 73, f. 2. 1834.?Type:

Brazil. Bahia, in lacubus ad Joazeiro [Juazeiro], 1819, Martius s.f?. (M!). Marsilea polycarpa var. mexicana A. Braun, Monatsber. K?nigl. Preuss.

Akad. Wiss. Berlin 1870: 713 (in clave). 1871.?Type: Mexico. Veracruz,

Mesachica, Dec 1828, Schiede 836 (holotype: B!; isotype: G!).

Plants forming diffuse colonies on mud or on floating vegetation. Rhizome

0.5-0.7 mm thick, green to black, sparsely to densely villous with tan hairs at

apices but glabrate proximally, nodal shoots elongated and resembling main shoot or condensed, nodal and internodal roots 0.2-0.4 mm thick, with internodes 0.8

5.5 cm long; rhizome in water 1.3-1.7 mm thick, green to brown, glabrous, internodes 5.3-11 cm long. Land leaves glabrous or with a few non-overlapping hairs, with green to brown, terete to canaliculate erect petioles 2.7-13 cm long, 0.4-0.6 mm thick, leaflets 0.6-3 cm long, 0.5-3.1 cm wide, rounded-spatulate to

flabellate; floating leaves with lax petioles 6.2-20 cm long, 0.5-0.9 mm thick, leaflets 2.4-3.4 cm long, 1.9-3.4 cm wide, rounded-spatulate; hydropoten uni

formly distributed. Fertile leaves produced on land, rarely on floating plants,

bearing 4-26 sporocarps on unbranched recurved peduncles 1.4-1.6 mm long, 0.2 mm thick, on the proximal half of the petiole in a row beginning 0.5-3 cm above

the petiole base. Sporocarps 2.0-2.6 mm long, 1.6-2.1 mm wide, 1.7-1.9 mm

thick, round to ovate in lateral view, round in cross section, brown to black,

thinly villous but eventually glabrate; raphe and teeth absent; sporocarp veins 10

11, unforked but intersected midway by a straight or zigzag transverse vein, free at tips. Sori 4-10 per sporocarp, borne on a sorophore that may be free at the tip or forming a complete ring, 3-7 microsporangia and 1-2 megasporangia per sorus. Microspores more than 50 per sporangium, 70-80 fim in diameter; 1-2

spores per microsporangium occasionally brown, misshapen, only 53 |xm long.

Megaspores 530-550 |xm long, 490-530 (xm wide, with an apical papilla 40-50 (xm

long. Figs. 4j, 5k, 13a-c.

Phenology. Produces sporocarps throughout the year, but most abundantly during the beginning of the dry season. Delascio (1980) reported that maximum

sporocarp production by M. polycarpa in Cojedes, Venezuela, occurred from

October through December. Marsilea polycarpa, like M. deflexa, appears to per sist through dry seasons only in the form of sporocarps; dormant rhizomes have not been found. If sufficient water is available, however, plants may be faculta

tively perennial; I found plants of M. polycarpa around small ponds in Venezuela at the end of the dry season.

Distribution. (Fig. 14). Marsilea polycarpa is a widespread species, occurring from central coastal Mexico through Central America and in the Greater Antilles south into South America, where it is largely confined to localities near the

Caribbean and Atlantic coasts; it has also been collected in the South Pacific on

the islands of Tahiti, Raiatea, and Bora Bora.

Marsilea polycarpa occurs on edges of marshes, ponds, and seasonal lakes on

clay substrates of slightly acidic to neutral pH. Its vascular macrophyte associates




include Scirpus cubensis Kunth, Hymenachne amplexicaule (Rudge) Nees, Neptu nia oler?cea Loureiro, and species of Ludwigia, Nymphoides, Eichhornia, Azolla,

Salvinia, and Mimosa.

In Venezuela, Marsilea poly carpa is common in the savannas of the Llano

region, where it grows on floating mats of vegetation in areas where the high water of the wet season can reach a depth of 1.5 to 2 m; the plants then root in

the mud when the waters recede.

Representative Specimens. Cuba. Laguna de Castellano, Baker 4228 (F, NY, US; f); Prov.

Santa Clara, Dist. Cienfuegos, Cieneguita SW, Combs 690 (B, F, K, MO, NY, P; f); Isla de Pinos

[Isla de la Juventud], near Nueva Gerona, Curtiss 220 (BM, CM, F, K, M, MO, NY, S, US; f); La

Habana, Anafe, Laguna de Ariguanabo, Ekman 212 (BM, C, G, GH, NY, S, UC, f except one at S); without definite locality, Wright 1799 (BM, G, K, MO, NY, US; f), Wright 1800 (BM, G, K, NY, US; f).?Jamaica. Clarendon Parish, Harris Savanna, Gillis 14970 (MSC f); Riverhead, near Ewarton,

Harris 8510 (BM, NY; f); Old Hope, Westmoreland, Harris 11827 (BM, C, CAS, F, GH, K, MO,

NY, P, S, US; f); Inverness, Lower Clarendon, Harris 12720 (BM, CAS, F, GH, K, MO, NY, US; f); St Catherine Parish, Riverhead, 2 mi SW of Ewarton, Proctor 6182 (PENN f); St Elizabeth Parish,

vicinity of Bamboo Avenue, Holland estate, Proctor & Mullings 21961 (U f); Pond Hodges from St

Elizabeths, Feb 1844, Purdie s.n. (BM, K; f); River Head near Ewarton, Underwood 1878 (NY, US;

f).?Haiti. Massif du Nord, Bayeux, en swamps al Guilloten, Ekman 4803 (BM, K, S; f).? Dominican Republic Civ. Santo Domingo, llano costero, prov. de Leybo, laguna Ojo del Rancho,

Ekman 12122 (C, S; f ); between Bayaguana and Guerra, Howard & Howard 9521 (B f, BM st, P st, S

f).?Puerto Rico. Laguna Yeguada [near Vega Baja], Britton & Britton 9718 (NY, S; f ), Britton et al.

6776 (NY, US; f); vie. Dorado, Button et al 6726 (F, G, NY, PH, US; f); vic. San Juan, Santurce, Britton & Cowell 1486 (F, NY, US; f); Mart?n Pe?a, Johnston 1311 (NY f); Vega Baja, laguna

Teguana, Sintenis 6790 (B, BM, CM, F, G, GH, K, M, MICH, MO, MSC, NY, P, PH, S, UC, US; f );

Dorado, Sintenis 6852 (K, P, U, US; f); Mart?n Pe?a, Stevenson & Stevenson 1677 (US f); N Coastal

Region, winter 1931-32, Thorp s.n. (PH f); near Loiza, Wagner 82020 (MICH f).?Mexico. Jalisco: 2

km N of Puerto Vallar?a in cultivated areas W of airport, Feddema 2532 (MICH f). Veracruz: in

paludibus limosis pr. Jicaltepec, Liebmann 2189 (BM, C; f).?Guatemala. Quezaltenango: Zanj?n de Oc?s, Bernoulli & Cario 144 (P f).?Honduras. Col?n: vic. Hacienda Tumbador de Alfonso

Midence, 25 km from Trujillo, Molina R. 30448 (ENCB, F, MO; f).?Costa Rica. Alajuela: vicinity of San Ram?n, Los Loros, Brenes 22653 (NY f).?Panama. Panam?: vicinity of Bejuco, Allen & Alston

1867 (GH, US, f ); near the big swamp E of the Rio Tecumen [Tocumen], Standley 26499 (CAS f, GH

f, US st); Nuevo San Francisco, Standley 30765 (GH, US; f).?Colombia. Atl?ntico: ci?naga cerca

de Monter?a y a los lados de la represa de Gu?jaro, Bristow 1 (COL f); region of Barranquilla, Pto

Colombia, Elias 1370 (COL, F, GH, P, US; f); Elias 1374 (F f); al sur de Ponedera, hacienda Puerto

Espa?a, Mora 1415 (COL f). Intendencia de Casanare: Yopal, Hacienda La Milagrosa, Carranza &

Arias 44 (COL f ).?Venezuela. Apure: lake ca 3 km N of Ca?o Caicara bridge on Bruzual-Mantecal

highway, Johnson 790 (MICH, VEN; f); pond along road from Mantecal to Elorza, ca 25 km N of

Elorza, Johnson 793 (MICH, VEN; f). Aragua: La Encrucijada entre San Juan de los Morros y

Calabozo, Aristeguieta 4151 (US, VEN; f). Barinas: Hato Mata Barbara, Ramia & Montes 5510

(VEN f). Bol?var: R?o Venamo, confluencia con el R?o Cuyun?, Dtto Roscio, SW de Tumeremo, Delascio & Lopez 8836 (VEN f ); Laguna Francos ca 1 km E of city limit of Ciudad Bol?var, Koyama & Agostini 7215 (GH, NY, VEN; f). Cojedes: Hato El Socorro ca 8 km N of El Ba?l, Johnson 784

(MICH, VEN; f ). Portuguesa: Dtto Guanare, La Aduana, creciendo en un estero cerca de Cacho de

Venao, Ortega & Griman 1913 (MICH, PORT, UC; f ). Terr. Delta Amacuro: Orinoco delta, Ca?o

del Uricoa, San Antonio, Bond et al. 131 (GH, NY, PH, US; f); Depto Tucupita, road between

Tucupita and La Horqueta, Steyermark et al. 114577 (NY, UC, VEN; f). Zulia: Dtto Maracaibo, carretera Perij?, entre Maracaibo y La Villa del Rosario, en km 28 de la via, Aristeguieta & Ferrer

12546 (UC, VZM; f).?Trinidad. Caroni Swamp, eastern edge, just off Princess Margaret Highway,

Jermy 10821 (BM f).?Guyana. Arnott s.n. (NY f); C.A.S., Mon Repos, East Coast Demerara, Davis

288 [R15] (K f); Zong en Vleight, Essequibo, Harris TP 380 (K f); Demerara, trenches, Coast

Region, 1897, Jenman s.n. (NY f); Central Agriculture Station, Mon Repos, East Coast Demerara, 7

Apr 1972, Omawale & Persaud s.n. (NY f); found on Coffee grove estate & sent home by the

Manager to C. S. Parker, Jun 1828, Parker s.n. (K f).?Suriname. Para River 2-4 km S of Houttu




inen, Kramer & Hekking 2742 (P, U, VEN; st); vie. of Republiek on the road Paramaribo-Zanderij, Schulz 9958 (K, U; f).?Brazil. Bah?a: Blanchet 2368 (G st, NY f); Blanchet2409 (G, P; f); Colonia Leopoldinia, Blanchet s.n. (NY f). Maranh?o: Perizes, Black et al. 54-16605 (BM f); Maraca?um? River Region, Campo do Casins, Fr?es 1858 (BM, F, G, K, MICH, MO, NY, S, U, US; f). Para:

Fazenda Tuiui?, Rio Arar? [Arar?a], Una do Maraj?, Black et al. 52-14264 (BM f ); marshes near Para

[Belem], Spruce 42 (K f); Spruce 417 (M f); Spruce s.n. (BM f, st, G f, P f). Terr. Roraima: S.

charcos, Rio Branco, Kuhlmann 916 (RB f); San Pedro, L?tzelburg 21231 (NY, UC; f): S?o Pedro am

Rio Branco, L?tzelburg 21239 (M f).-Society Islands. Otaheite [Tahiti], 1769, Banks s.n. (BM f);

Raiatea, Uturoa, Moore 116 (KLU f); Bora Bora, Turapuo, St. John 17414 (K, MICH; f).

Although the fertile fronds of M. polycarpa can vary greatly in size, its sporo carps are remarkably uniform in size and shape. The numerous small sporocarps,

lacking raphes and teeth and borne on short slender peduncles, and their distinctive

attachment in a row make this species easy to identify. Marsilea crotophora (no. 5) has a similar attachment and number of sporocarps, but its uppermost sporocarp is

usually placed above the midpoint of the petiole, and its sporocarps are larger. In sterile condition, M. polycarpa may be recognized by its tendency to have

floating rather than submerged rooted rhizomes, with the leaves consequently

short-petioled, and the occurrence of hydropoten all the way to the pulvinus; these characters separate M. polycarpa from M. deflexa (no. 3). The rhizomes

and petioles of M. polycarpa are usually more slender and less hairy (on land) than those of M. crotophora.

M. polycarpa is most closely related to M. crotophora; both have many small

non-angled sporocarps that are attached in a row on the petiole. There is also strong resemblance of M. polycarpa to an undescribed species collected by Corner in Ma

laya (Corner s.n., 1941, S.F.N. 38109, BM), but the latter, represented by only a

petiole fragment, has obovoid sporocarps 3.8 mm long on peduncles 5-6 mm long. In Guyana, M. polycarpa is used occasionally as a potherb (Omawale 1973).

A Polynesian common name for the plant, recorded in the fieldbooks of Joseph Banks at the British Museum, is patoa, or pataa.

Martius, in describing M. brasiliensis, cited Marsilea polycarpa Hooker &

Greville in synonymy, but followed this citation with a question mark; I thus

consider Martius's name to be valid but do agree that it is synonymous with M.

polycarpa. The herbarium name Marsilea caribaea, which occasionally appears in

publications (e.g., Eames 1936), applies to this species.

5. Marsilea crotophora D. M. Johnson, sp. nov.?Type: Brazil. Mato Grosso do Sul: Corumb?, 14 Oct 1972, Hatschbach & Scherer 30470 (holotype: US!;

isotypes: C! LP! M! MICH! NY! UC!).

Rhizoma crassa, 1.0-1.8 mm lata, viridis vel badia, apiciter tomentosa demum

glabrata, surculis lateralibus condensatis, radicibus ad et inter nodos 0.3-0.5 mm

latis, internodis 1.8-5 cm longis; rhizoma sub aqua 1.1-2.3 mm lata, viridis vel

brunnea, glabra, internodis 4.2-9 cm longis. Folia terrestres sparsim pubescentia demum glabrata, petiolis virido-brunneis, crassis, teretibus vel canaliculatis, 3.6-15 cm longis, 0.8-1.5 mm latis, et foliolis spathulatis vel flabellatis, longioribus (1.3-3.7 cm) quam latioribus (1-3 cm); folia natantia non vidi. Folia fertilia insidens terrae vel

aquae formata, sporocarpiis 5-20 portatis in pedunculis uncinatis obliquis 1.7-2.7 mm longis et 0.3-0.4 mm latis; sporocarpia crebera, sporocarpio ?nfimo portato 1.1




7.5 cm supra basim petioli et sporocarpio summo plerumque portato supra medium

petioli. Sporocarpium 3.1-3.9 mm longum, 2.9-3.7 mm latum, 1.2-2.2 mm eras

sum, rotundum vel pyriformis aspectu laterali, ellipticum angustum vel ovatum as

pectu frontali, tomentellum, fuliginosum vel nigrum, crassum, raphe et dentibus

absentibus; vena lateralis 18-20, non ramosa, vena transversis valde flexuosis inter

cepta (Fig. 9e). Sori 10-13 intrasporocarpiam, microsporangiis 10et megasporangiis 3-4 intra sorum. Solum sori immaturi vidi, microsporis 40-50 (xm di?metro, et

megasporis 440 |xm longis, 330-370 jjum latis, ferentibus papillam apicalem 40 |xm

longam. Figs. 2b, 4k, 51, 9e, 13j, k.

Phenology. I have seen fertile collections of this species from February-April, June, and August-October.

Distribution. (Fig. 14). Marsilea crotophora inhabits ditches and lake margins in Veracruz and Tabasco, Mexico, Nicaragua, Venezuela, western Brazil, Bolivia, and Paraguay. The many sterile collections of Marsilea from along the Upper

Amazon, including one provisionally named Marsilea stratiotes by Braun (1871), may also represent this species.

Specimens Examined. Mexico. Veracruz: cerca de Lerdo de Tejada, rumbo Alvarado, Lot 1295

(BM, GH, MEXU, MO; f). Tabasco: 25 mi N of Villahermosa on road from Frontera, Saunders 231

(US f).?Nicaragua. Granada: Granada, Baker 2281 (G, GH, K, M, MICH, MO, NY, P, S, TEX,

UC, US; f); vie. Grenade, L?vy 268 (C, G, P; f).?Venezuela. Barinas: du r?o Guanaparo, affluent

de l'Apure, 1893-94, Geay s.n. (P f).?Brazil. Amazonas: Rio Negro, Fazenda Sto Antonio, Fro?s

24-865 (RB f). Mato Grosso do Sul: Corumb?, Hoehne 5783 (R f); Pequi, Rio Paraguai, above

Acurizal, Prance ?tal 26143 (NY f).?Bolivia. B?ni: Trinidad, Krapovickas & Schinini35030(CTES,

MICH; f); Prov. Cercado, a 15 km de Trinidad, camino a Sachojere, Rolleri 9 (US f).?Paraguay. Capital: Asunci?n, laguna del Parque Trinidad, Rojas 8828 (SI f).

Good specimens of M. crotophora are readily distinguishable from those of its

closest relative, M. poly carpa (no. 4), by the more massive rhizomes and petioles, and by the larger, more crowded, more pearshaped and flattened sporocarps, the

lowermost of which is attached well above the petiole base, and the uppermost of

which may be borne two-thirds of the way up the petiole. The plumose roots present on many specimens of M. crotophora suggest

that, like M. poly carpa, it is often free-floating; unlike M. poly carpa, however, M. crotophora often has fertile (presumably emergent) leaves in this floating

condition.

The specific epithet, meaning "tick-bearing," refers to the row of tickshaped sporocarps fastened to the petiole.

Putative Hybrids Between Members of Marsilea Section Clemys

3. Marsilea deflexa x 4. Marsilea polycarpa.?Figs. 13d, 14.

Specimens Examined. Venezuela. Apure: experimental areas just S of Mantecal, Davidse 3831

(UC f); road from Mantecal to Elorza, ca 50 km N of Elorza, Johnson 792 (MICH, VEN; f).

This taxon combines the small (2.7-3.1 mm long) sporocarps (Fig. 13d) of M.

polycarpa and the low number (1-3) of sporocarps per leaf of M. deflexa. The

attachment of the lowest sporocarp is higher above the base of the petiole than in

M. deflexa, which also suggests a genetic contribution by M. polycarpa.




The population of this hybrid that I examined in the field was growing at the

edges of a pond, a habitat in which I also found M. deflexa and M. polycarpa in

the same region of Venezuela. Neither of the putative parents was found growing with the hybrid, however.

3. Marsilea deflexa x 5. Marsilea crotophora =Marsilea xsubangulata A. Braun

(pro sp.), Monatsber. K?nigl. Preuss. Akad. Wiss. Berlin 1870:723.1871.?

Type: Venezuela. Caracas [actual locality given by Ernst in Vargasia (1868) as Anauco, probably in the state of Miranda, fide A. R. Smith], Feb 1870, Ernst s.n. (lectotype, here designated: B!).?Figs. 13i, 14.

Specimens Examined. Colombia. Huila: 1 km E of Neiva, Huila, Little 9253, 9254 (COL f).? Venezuela. "Caracas," 19 May 1870, Ernst s.n. (B f); "Caracas" [probably from same locality as

Ernst specimen], May 1874, Kuntze s.n. (NY f).

This taxon is similar to the previous one, but the specimens have 4-11 some

what angular sporocarps 3.1-3.8 mm long per leaf (Fig. 13i). In one specimen

(Little 9254) sporocarps were present on floating leaves. The slightly angular sporocarps and sporocarps on floating leaves of this taxon suggest M. deflexa as

one parent; the slightly larger sporocarps of this hybrid as compared to the previ ous one suggest M. crotophora rather than M. polycarpa as the other parent.

III. Marsilea section Nodorhizae D. M. Johnson, sect. nov.?Type: Marsilea ves

tita Hooker & Greville.

Marsileae radicibus limitatis ad nodos, surculis lateralibus condensatis con

spicuis plerumque hirsutis, sporocarpiis 1-4, 2.5-9.0 mm longis, raphe, dente

inferiore, et dente superiore sporocarpii praesentibus, nervis later alibus sporocar

pii vena transversis intercepts absentibus, et soris 10-23 intra sporocarpiam. This section consists of six New World species and one (treated here) from

Hawaii.

6. Marsilea ancylopoda A. Braun, Monatsber. K?nigl. Preuss. Akad. Wiss. Berlin

1863: 434. 1864. Zaluzianskia ancylopoda (A. Braun) Kuntze, Revis, gen.

pl. 2: 823. 1891.?Type: Ecuador. Environs of Guayaquil, 1847, Jameson 394 (holotype: G!; isotypes: BM! G! K!).

Marsilea ernestii A. Braun, Monatsber. K?nigl. Preuss. Akad. Wiss. Berlin 1870: 746. 1871. Zaluzianskia ernestii (A. Braun) Kuntze, Revis, gen. pl. 2:

823. 1891.?Type: Venezuela. "Caracas" [actual locality Anauco, given

by Ernst in Vargasia (1868), which is probably in the state of Miranda, fide A. R. Smith], 1870, Ernst s.n. (holotype: B?; isotype: NY!).

Marsilea berteroi A. Braun, Monatsber. K?nigl. Preuss. Akad. Wiss. Berlin 1870: 747. 1871. Zaluzianskia berteroi (A. Braun) Kuntze, Revis, gen. pl. 2: 823. 1891.?Type: S. Dominique [Hispaniola], 1821, Bertero s.n. (G!).

Marsilea mexicana A. Braun, Monatsber. K?nigl. Preuss. Akad. Wiss. Berlin

1870: 747. 1871. Zaluzianskia mexicana (A. Braun) Kuntze, Revis, gen.

pl. 2: 823. 1891.?Type: Mexico. Julisca [Jalisco], Beechey s.n. (K!). Marsilea concinna Baker, J. Bot. 24: 279. 1886. Zaluzianskia concinna




(Baker) Kuntze, Revis, gen. pi. 2: 823. 1891.?Type: Paraguay. Marshes

near Assumption [Asunci?n], Jun 1874, Balansa 1127 (holotype: K!; iso

types: G! P! S!). Marsilea hickenii Herter, Anales Mus. Nac. Montevideo 2(1): 379. 1925.?

Type: Uruguay. Soriano, ?guila, Nov 1895, Osten 3210 (B?).

Plants forming dense mats or turfs of overlapping rhizomes. Rhizome 0.5-0.9 mm thick, dark red to black, covered with rusty hairs at the apices but glabrate

proximally, bearing short nodal shoots, nodal roots 0.1-0.3 mm thick (rarely a

few roots displaced 2-3 mm internodally), internodes 0.7-2 cm long; rhizomes in

water 0.5-1.0 mm thick, green, glabrous, with internodes 1.9-14 cm long. Land

leaves with stiff erect terete petioles 1-18 cm long, 0.3-0.6 mm thick, leaflets

0.2-1.7 cm long, 0.1-1.6 cm wide, frequently wider than long, linear (small) to

flabellate (large), covered with non-overlapping hairs or glabrous, rarely with the terminal margin crenate; floating leaves with green flexuous petioles 10-12 cm

long, 0.2-0.9 mm thick, leaflets 0.9-2.7 cm long, 0.8-2.4 cm wide, obovate to

flabellate; hydropoten irregularly distributed or absent. Fertile leaves produced on land (rarely in water), bearing solitary sporocarps at the petiole base on a

spreading or retrorse peduncle 3-11 mm long, 0.3-0.4 mm thick, often hooked near the apex. Sporocarps (2.5-) 4.0-6.0 mm long, (2-) 2.5-5.0 mm wide, 2.1 3.2 mm thick, rectangular to round in lateral view, narrowly elliptical to nearly round in cross section, covered with a shaggy pelt of white to fulvous hairs but

eventually glabrate; raphe 0.8-1.4 mm long, inferior tooth 0.2 mm long or absent,

superior tooth absent or a broad bump 0.1 mm high; sporocarp veins 15-16,

forking midway, anastomosing at the tips and occasionally midway. Sori 14-22

per sporocarp, attached to a sorophore with a free acute tip, 20-40 microsporan gia and 2-7 megasporangia per sorus. Microspores more than 60 per sporangium, 50-80 |xm in diameter. Megaspores 470-640 jxm long, 385-515 |mm wide, with an

apical papilla 45-80 fim long. Figs. 2e, 4f, 5i, 9c, 10b, 15e, f.

Phenology. Produces sporocarps throughout the year if sufficient water is

available, but dies back completely by the end of the dry season, then presumably perennating solely by sporocarps.

Distribution. (Fig. 16). Throughout its range M. ancylopoda grows in dense

clays, usually on the borders of temporary ponds and ditches, at elevations from sea level to 2400 m in otherwise arid regions such as the Pacific dry forests in

Mexico and Costa Rica, the desert of Falcon, Venezuela, and the quebrachales of northern Argentina and Paraguay. In these habitats it occurs with macrophytes such as species of Eleocharis, Paspalum, Ludwigia, Echinodorus, and Phyla, and, in deeper water, Egeria and Najas. At one site near Coro, Venezuela, R. Wing

field (pers. comm.) found that all of the macrophyte associates of M. ancylopoda, with the exception of Eleocharis elegans, were annuals, a fact perhaps related to the temporary nature of the habitats. In Argentina, the plants are absent from

apparently suitable aquatic sites on sandy substrates, which are dominated by Thalia, Pistia, and Salvinia.

Marsilea ancylopoda has a wide but discontinuous distribution from western Mexico and the Greater Antilles south through Central America into northern South America; south of the Amazon it occurs in eastern Brazil and the lower Paran? River basin. Specimens of Marsilea collected by Nash and Underwood in




FIG. 15. Morphology of Marsilea macropoda and M. ancylopoda. M. macropoda: a. habit; b.

sporocarps borne on branched peduncle; c. sporocarps with ind?ment removed to show variation in

shape; d. variation in attachment of sporocarps. M. ancylopoda: e. habit; f. sporocarps to show

variation in shape and in orientation of peduncle. (Scale: short bar-a, e; long bar-b, c, f.)




FIG. 16. Distribution of Marsilea ancylopoda, M. minuta, M. mollis, M. nashii, and of sterile

Andean specimens (M. mollis vel aff.).

Florida, U.S.A., in the 1890's, and identified as M. vestita in the literature (Sta son 1926; Ward & Hall 1976), are not typical but appear to be this species.

Representative Specimens. U.S.A. Florida: Lake Co., vie. Eustis, Nash 831 (F, G, K, MICH,

MO, NY, UC, US, Z; f); Orange Bend, Underwood 337 (US f); Underwood 2305 (NY f).?Jamaica. Near Treasure Beach, Barkley & Proctor 38651 (COL f, GH st). Near Curatoe Hill, 1.5 mi S of May

Pen, Proctor 11534 (BM, U; f). St. Catherine Par., Naggo Head, Proctor 27609 (ENCB, TEX; f). St.

Elizabeth Par., 0.3 mi ENE of Great Bay, Proctor 29976 (F f).?Puerto Rico. Between Ponce and

Santa Isabel, Britton & Britton 7340 (NY, US; st). Vicinity of Boquer?n, Britton et al. 8872 (G, NY;

f ). Guanica, in litore ad Laguna, Sintenis 3805 (BM, CM, F, G, K, M, MICH, MO, MSC, NY, P, PH,

S, U, UC, US, Z; f).?Mexico. Nayarit: Tepic, Jones 23510 (MO st, UC f ); 2.2 mi E of Las Varas on

Hwy 200, Murray & Johnson 1458 (MICH f ).?Guatemala. Huehuetenango: Huehuetenango, Stand

ley 65703 (F f ); ruins of Zacaleu near Huehuetenango, Williams et al. 22416 (F, LL; f ). Santa Rosa:

Aguacaliente, Kellerman 7721 (NY f).?Honduras. Comayagua: vicinity of Siguatepeque, Standley 56292 (F st). Morazan: R. Yeguare a Guinope, Rodriguez 1583 (F f ). El Para?so: vicinity of Danli,

Standley 16616 (F f ).?Nicaragua. Matagalpa: 9 km S of Sebaco, Harmon & Fuentes s.n. (ENCB f);




rt 1 S of Dario, Calabazas, Seymour 2576 (BM, GH, NY, US; f). Department unknown, 1853-56,

Wright s.n. (US f).?Costa Rica. Guanacaste: road to Paloverde, 3 km past turnoff to Refugio and

ca 10 km E of Paloverde, Murray & Johnson 874 (MICH f).?Panama. Cocl?: El Valle de Ant?n, Alston 8840 (BM f).?Colombia. Cundinamarca: Mun. de Sop?, carretera de Hato Grande a Cajic?, antes de llegar al r?o Bogot?, Acosta A. 785 (COL f). Tolima: Espinal-Giradot, Alston 7698 (BM

st).?Netherlands Antilles. Bonaire: Sabana, Amoldo 408 (U f); near Kralendijk, Amoldo 497

(U, US; f ); Dam bij Jatoe Bacoe, Stoffers 654 (U f).?Venezuela. Carabobo: between Valencia and

Yuma, Alston 5639 (BM f); Alston 5874 (BM f); Porto Cabello, 1889, Goebel s.n. (M, P; f). Falc?n:

ca 2 km E of Huequito, Johnson 777 (CORO, MICH, VEN; f ); Coro-Maracaibo Hwy at km 331, ca 5

km E of Llano Grande and 23 km E of bridge over R?o Salado, Johnson 780 (CORO, MICH, VEN;

f ); carretera Coro-Mor?n, 100 km E of Coro, Werff3518 (MO, U, UC; f ); entre Capatarida y Boroj?, 16 km por la carretera del oleoducto, Wingfield 6778 (MICH, MY, UC, VEN; f ); Bejuquero, 18 km S

of Coro, Wingfield 7042 (MICH, MY, UC, VEN; f); pozo al margen sur de la ci?naga Santa Ana, 14

km E de Puerto Cumarebo, Wingfield 8147 (CORO, MICH, MY, VEN; f). Lara: Barquisimeto, Alston 6354 (BM f ). Sucre: Peninsula de Araya, ca 4 km W of Caimancito, Liesner & Gonz?lez 12125

(UC st). Zulia: pond on western outskirts of Maracaibo, Johnson 781 (MICH, VEN; f); Sta. Rosa de

la Tierra, cerca de Maracaibo, Pittier 10697 (G, GH, NY, VEN; f).?Brazil. Bah?a: valley of the Rio

das Ondas, ca 5 km E of Barreiras, Irwin et al. 31630 (C, F, K, NY, US, Z; f ); bei Calder?o, Ule 7238

(G, K, S; f ). Rio Grande do Sul: St. Hilaire 2652 (P st).?Ecuador. El Oro: Piedras, Andr? 1899 (F,

GH, K, NY; st). Guayas: Guayaquil, Asplund 15265 (G, LL, NY, P, R, US, Z; f); Km 48 on road

Guayaquil-Jipijapa, between San Isidro Ayora and Loma de Sargentilla, Holm-Nielsen et al. 7220 (F

st, NY f); Chanduy, Spruce 6550 (BM, G, K, P, S; f); Salinas, Svenson 11152 (GH, NY, US; f).? Peru. Tumbes: lagoon of "Salitral grande," Coronado 235 (GH, UC; f).?Paraguay. Chaco: R?o

Verde, Herter 84810 (S, Z; st); Mayor Pedro Lagerenza, 20?S, 60?45'W, Cauce del R?o Timane,

Schinini & Bordas 14834 (CTES st).?Uruguay. Maldonado: Maldonado, Punta Ballena, Castellanos

17496 (LL f). Montevideo: Montevideo, Arechavaleta 461 (P f); Gibert 1320 (NY, US; st); Santiago

V?squez, Herter 844 (G, M, MO, NY, S, U, UC, Z; st); Herter 844c (G, GH, MO, NY, SI, S, U, UC,

US, Z; f).?Argentina: Buenos Aires: Station de San Vicente, pr?s de Buenos Aires, Balansa 1884

or 1885 (BM, K, G, P; f ); R?o Lujan, Mercedes, Burkart 449 (GH f ); Los Talas, Cabrera 7250 (LP f ); alred. de Cap. Federal, Isla Mart?n Garc?a, Castellanos 672 (BA f ); El Toro, Daguerre 230 (BA f ); km

77, road to Mar del Plata, 20 km S Dolores, Eyerdam et al. 23283 (G, K, UC, US; f ); Mar del Plata,

camino a Laguna Ponce, Hicken 506 (SI f); La Plata, Spegazzini 17791 (LP f); prope Buenos Aires,

Spegazzini 17794 (LP f). Chaco: Depto Donovan, 13 km N de La Verde, Ea. Dos Tranqueras, Schinini 22732 (MICH f ); Resistencia, 8 Jul 1976, Volk s.n. (BA f ). C?rdoba: Valle de los Reartes, 20

Jan 1919, Castellanos s.n. (SI f); Cintra, 12-3-1966, Partridge s.n. (BA f); Cordoba, Stuckert 15811

(G, SI; st). Corrientes: Yapey?, Burkart 8020 (SI f); Depto San Cosm?, road to Ing. Primer Corren

tino, 2 km N of Santa Ana, Johnson 769 (MICH f ); Depto Capital, Arroyo Pirayui, Mart?nez Crovetto

10179 (CTES f); Depto Mburucuy?, Estancia Santa Teresa, Pedersen 1109 (C, CTES, G, GH, NY, SI,

US; st); Depto Mburucuy?, Estancia Santa Mar?a, Pedersen 3980 (C, G, GH, K, LL, MO, NY, S, U,

US; f); Depto Empedrado, Estancia La Yela, Pedersen 9823 (C, CTES, GH, K, LP, MO, NO, NY, P,

S, UC; f ). Depto Santo Tom?, 35 km SW de Santo Tom?, Arroyo Cuay Grande, Schinini et al. 16727

(CTES st). Entre R?os: Parque Rivadavia, Burkart et al. 30220 (SI f); Concordia, Burkart & Troncoso

26116 (SI f ); Depto Galaguay, La Calera, Burkart & Troncoso 27161 (SI f ); Federaci?n, Burkart et al.

30219 (SI f); Depto Paran?, Berduc, Palmar de Col?n, Burkart 24702 (SI f); Depto Uruguay, 15 km al

sur de Concepci?n del Uruguay, Burkart 26671 (SI f). Formosa: Ing. Ju?rez, Burkart 20188 (SI f);

Depto Pilcomayo, Ruta 11 Clorinda-Formosa km 4, Morel 1570 (GH, MO; f ); Depto Pilcomayo, Ruta

11 Clorinda-Formosa al km 3, Morel 1587 (GH f, MO st). Jujuy: Depto Capital, La Almona, Cabrera

et al. 26139 (LP st). Mendoza: Payun Matru, cerca de Los Ranguiles, 30 Jan 1941, Castellanos s.n.

(BA f). R?o Negro: (Valle) Region de Conesa, Scala 70 (LP, SI; st). Salta: On Hwy 34 S of Tartagal, 5 km NE of Embarcaci?n, Johnson 758 (MICH f); entre el pasaje de R?o Juramento y Cabeza del

Buey, Lorentz & Hieronymus 522 (BM f, F st, G st, K f, NY st, P f, st, S st, US st, Z st). San Luis:

Pancanta, cumbre de la Sierra, Pastore 416 (BA f). Santa Fe: camino a Helvecia, Tur 696 (LP f);

Laguna de La Gallareta, 5 Jan 1937, Castellanos s.n. (BA f).

The sporocarps borne on recurved peduncles, thus developing and maturing

underground, are unique among New World marsileas, but also occur in the

African M. vera, M. distorta, and M. subterr?nea (Launert 1968). In addition to




the recurved or horizontal peduncle, however, the species may be distinguished from other members of the section by the broad, virtually glabrous leaflets and

the pelt of appressed hairs that covers the sporocarp. The sporocarps are usually

significantly larger than those of M. mollis, but occasional individuals have been

found (e.g., Wingfield 6778 from Venezuela and Volk s.n. from Argentina) that

have leaves, rhizomes, and sporocarps reduced in size. These dwarfed plants retain the peduncle that is hooked at the apex and the reddish brown sporocarp hairs typical of M. ancylopoda.

Specimens of this species collected in Florida by Nash and Underwood do not

have peduncles that are as strongly geotropic or as strongly hooked as those of

many specimens. The absence of a superior tooth on the sporocarps and the

covering of reddish brown hairs on the sporocarps of these specimens, however, characterize them as M. ancylopoda.

The species M. ancylopoda, M. ernestii, M. berteroi, and M. mexicana de

scribed by Braun have hitherto always been considered distinct, probably because

they were believed not to overlap in range. Thus it was easy for compilers of local

floras to choose the name that applied to their geographic area: M. berteroi for

the West Indies and Central America, M. ernestii for northern South America, and M. ancylopoda for western South America. To separate the species morpho

logically, however, Braun (1871) used length of the peduncle relative to the

length of the sporocarp, which is too variable to be used so precisely as a taxo

nomic character in Marsilea. That, coupled with filling of range gaps among the

species described by Braun with collections from Costa Rica, Panama, and Co

lombia, has led me to combine the four species, as well as two more from south ern South America, M. concinna and M. hickenii, in M. ancylopoda.

In his publication of M. ancylopoda in 1863, Braun cited James 394 as the

type but later (1871) corrected that to read Jameson 394. The epithet ancylopoda means "bent or hooked foot," referring to the recurved peduncle, and is not

spelled "ancyclopoda" as often appears in the literature.

The place of publication for M. ernestii A. Braun is usually cited as Sitz

ungsber. Ges. Naturf. Freunde Berlin 1870: 46. (1871), but Braun provided no

diagnosis or description there, and the name must therefore date from his publica tion in Monatsber. K?nigl. Preuss. Akad. Wiss. Berlin later in the same year.

The protologue for M. hickenii Herter lists the type, Osten 3210, as being at

B, but it was not included in the loan I received of their material, and I have not

seen isotypes. The original description of M. hickenii fits M. ancylopoda quite well, and I have seen a number of specimens identified by Herter as M. hickenii

that likewise cannot be separated from M. ancylopoda; I am therefore confident

in placing Herter's name in synonymy here.

7. Marsilea oligospora Goodding, Bot. Gaz. (Crawfordsville) 33: 66. 1902.?Type:

U.S.A. Wyoming: Teton Co., Jackson's Hole, 12 Aug 1899, Nelson &

Nelson 6560 (holotype: RM!; isotypes: CM! G! GH! K! MO! RM! UC!).

Plants forming dense colonies. Rhizome 0.4-0.7 mm thick, reddish brown to

black, apices densely covered with tan to tawny hairs, bearing well developed, densely hairy nodal shoots, nodal roots 0.2-0.4 mm thick, internodes 0.8-1.4 cm

long; rhizomes in water 0.5-0.7 mm thick, green to brown, glabrous, internodes




0.8-2.1 cm long. Land leaves with sinuous and somewhat spreading to erect green to coppery petioles 3.1-5.7 cm long, 0.3-0.5 mm thick, leaflets 0.6-1.5 cm long, 0.5-1.4 cm wide, obtriangular, pilose, with straight lateral margins and a faintly crenulate terminal margin; floating leaves with lax petioles ca 15 cm long, 0.2-0.3

mm thick, leaflets 0.9-1.2 cm long, 0.9-1.4 mm wide, broadly cun?ate; hydro poten irregularly distributed. Fertile leaves produced on land on short nodal

shoots only, bearing solitary sporocarps at the base on erect peduncles 5-10 mm

long, 0.3 mm thick, that may be bent toward the sporocarp at the base of the

raphe. Sporocarps 5-6 mm long, 3.6-4 mm wide, 1.5 mm thick, nodding, ovate in

lateral view, elliptical in cross section, laterally often faintly ribbed, tan to black, covered with long hairs when young but eventually glabrate; raphe 0.8-1.0 mm

long, inferior tooth 0.2-0.6 mm long, blunt and slightly curved away from the

sporocarp, superior tooth up to 0.4 mm long, broad, blunt, or absent; sporocarp veins ca 24, branching lA distance from base, sometimes anastomosing at tips. Sori

14-20 per sporocarp, attached to a ringshaped sorophore, 30-40 microsporangia and 4-8 megasporangia per sorus. Microspores 48-64 per sporangium, 55-70 jxm in diameter. Megaspores 610-680 |xm long, 390-480 (xm wide, with an apical

papilla 40-50 |xm long. Figs. 4a, 5h, 9a, 17j, k.

Phenology. Sporocarps produced June-October, persisting in nature at least

until the following growing season.

Distribution. (Fig. 18). Occurs around ponds and marshes at 700-2400 m, also found in wet depressions in sagebrush and less commonly on river margins.

Distributed across the northern fringes of the Great Basin from the western side

of the Continental Divide in Montana and Wyoming west to the Cascades and

Sierra Nevada in Washington and California.

Representative Specimens. U.S.A. California: El Dorado Co., Fallen Leaf Lake, S end of Lake

Tahoe, 12 Aug 1906, Fisher s.n. (US f ). Lassen Co., near Eagle Lake, 25 Jul 1894, Baker & Nuttings.n.

(UC f). Modoc Co., Mud Lake 35 mi S of Tule Lake, Stebbins 4013 (UC f); Boles Creek between Crowder Flat and Clear Lake, Toren & Trowbridge 5313 (CAS f); Fletcher Creek at Pease PL, Devil's

Garden, Wheeler 3975 (F, GH, NY, Z; f); Everly Reservoir, Devil's Garden, Wheeler 3993 (G, GH,

NY, RM; f). Plumas Co., E side of Red Clover Valley on Beckwourth-Milford Road, Plumas National

Forest, Enter 3894 (NY f). Sierra Co., Lemmon 227 (CM, G, GH, K, MO, NY, PH, R; f); Sierra

Valley, 1874, Lemmon s. n. (GH f, MICH f); Lemmon s.n. (CAS, US-55014; f). Trinity Co., Big Flat, Howell 13215 (CAS, GH, US; f ). Idaho: Canyon Co., New Plymouth, MacBride & Payson 3844 (CAS,

CM, GH, K, MO, RM, UC, US; f). Cassia Co., Shoshone Ranger Station, Minidoka National Forest,

Gierisch 718 (GH f). Elmore Co., King Hill, Nelson & MacBride 1158 (CAS st, F st, GH st, MO f, NY

st, RM f, UC st, US f, WS st). Kootenai Co., 2 mi SW Coeur d'Alene at The Meadows, Christ 19130

Y f); near Spokane Bridge, 20 Aug 1892, Heller s.n. (PH f). Nez Perce Co., Clearwater River opp.

Lewiston, St. John 6790 (UC, WS; f). Washington Co., 4.5 mi SW of Weiser, along the Snake River, Christ 12915 (NY f ). Montana: [Missoula Co.?], along Blackfoot River, Canby 400 (MO f, NY f, PH f & st, US f). County unknown, Big Blackfoot Valley, Watson 470 (GH, PH; f). Nevada: Elko Co., Thatcher Slough NW of Owyhee, Williams 79-136-3 (NY f). Washoe Co., Wadsworth, 22 Jul 1887,

Tracy & Evans s.n. (NY f, US f). Oregon: Klamath Co., SE of Klamath Falls, Lawrence2154 (UC f, US f). Malheur Co., T40S, R40E, Sec. 21, Farley 78-41 (NY f). Morrow Co., 10 mi W of Boardman,

Thompson 4882 (CAS, GH, MO, PH, US; f ). County undetermined, Snake River, Cusick 1007 (F, G;

f). Utah: Cache Co., 4 mi NE of Brigham City at Dry Lake, Anderson 1299 (NY f); Dry Lake near

Wellsville, Jul 1924, Flowers s.n. (NY f); Dry Lake, Garrett5375 (F f); Dry Lake 13 mi NE of Brigham City, Harrison & Garren 10505 (UC f); 14 mi S Logan, Dry Lake, Sardine Canon, Tillen 185 (NY, UC; f). Washington: Klickitat Co., Falcon Valley, Suksdorf 227(GH f); 7 Nov 1883/29 Aug 1884, Suksdorf s.n. [716] (BM, C, F, M, MO, NY, PH, US, WS; f). Lincoln Co., near Crest?n, Thompson 9166 (MO,

NY; f); E of Crest?n, Thompson 11676 (CAS, DS, MO, NY; f). Spokane Co., Spokane Bridge, 18 mi E




Fig. 17. Morphology of Marsilea villosa, M. nashii, M. vestita, M. oligospora, and M. mollis. M.

villosa: a. two leaves; b. sporocarps with hairs; c. old sporocarp without hairs. M. nashii: d. two

sporocarps to show variation in size and in orientation of peduncle; e. two leaves. M. vestita subsp.

tenuifolia: f. two leaves; i. sporocarp. M. vestita subsp. vestita: g. habit of plant from California; h. five

sporocarps to show variation in size and in length of peduncle. M. oligospora: j. two leaves; k. two

sporocarps. M. mollis: 1. two sporocarps from the same collection, the larger from a plant in cultiva

tion; m. two leaves. (Scale: short bar-a, e, f, g, j, m; long bar-b, c, d, h, i, k, 1.)




Fig. 18. Distribution of Marsilea vestita subsp. vestita, M. oligospora, and M. macropoda in North

America. Inset: disjunct locality of M. vestita subsp. vestita in Peru.

of Spokane, Sandberg 901 (BM, CAS, DS, GH, K, NY, US; f). Whitman Co., Pullman, Pickett s.n.

(MICH f); Pullman, Piper 1736 (CAS, MO, WS, Z; f). County unknown, 1906, Gandoger s.n. (G f). Wyoming: Sublette Co., Kendall, Payson & Payson 2920 (F, GH, MO, NY, PH, RM, UC, US; f); near New Fork Lake, Payson & Payson 4437 (GH f, MO f, MSC f, PH f, RM st, UC f, US f, st, WS

f). Teton Co., Grand Teton National Park, 3 mi N of Colter Bay, Porter & Porter 9399 (CAS, MSC,

NY, RM, UC; f ); Grand Teton National Park, Square G Ranch NE of String Lake Campground, 20

Jul 1953, Prettyman s.n. (CAS, TEX, UC; f).




The combination of long-peduncled nodding sporocarps with an indistinct

superior tooth and of rhizomes and leaves that are pilose separate M. oligospora from the sympatric M. vestita (no. 10). Although Stason (1926) showed that

number of megaspores per sorus varied too widely to be used to distinguish these two species, as Goodding believed when describing A?. oligospora, it is true that M. oligospora generally has fewer megaspores (4-8) than does M.

vestita (9-15). Stason (1926) concluded from her study that M. vestita and M. oligospora

were conspecific, allowing that perhaps M. oligospora could be considered an

"ecospecies;" recent floristic works (e.g., Cronquist et al. 1972; Mickel 1979;

Lellinger 1985) have followed her treatment. I found M. oligospora to differ

consistently in a number of characters despite sympatry with M. vestita over part of its range. In its spreading lax hairs, relatively long wiry penduncles, and ab sence of a superior tooth on the nodding sporocarp, M. oligospora resembles the

following species, M. mollis.

Goodding chose the epithet oligospora to indicate that he believed that this

species had fewer megaspores per sorus than did M. vestita. On the printed label

of the holotype of M. oligospora the locality has been corrected in pen to read

"Teton Co., Jackson's Hole;" on all isotype sheets I have seen the uncorrected

label reads "Uinta Co., Jackson's Lake."

8. Marsilea mollis Robinson & Fernald, Proc. Amer. Acad. 30: 123. 1895.?Type: Mexico. Chihuahua, San Diego, 20 Apr 1891, Hartman 604 (holotype: GH!; isotypes: F! GH! MSC! NY! UC!).

Marsilea punae Sota, Darwiniana 20(1/2): 226. 1976.?Type: Argentina. Ju

juy Prov., Depto Yavi, 27 Oct 1967, Werner 842 (holotype: LP!; isotype: SI!).

Plants forming dense colonies with overlapping rhizomes. Rhizome 0.5-1.3 mm thick, light brown to black, pilose at the apices but glabrate proximally, bearing weakly to strongly developed nodal shoots, these densely pilose and often

themselves with lateral branches, roots 0.1-0.3 mm thick at nodes (occasionally with an internodal root 5-10 mm from node), internodes 0.8-2.3 cm long; rhi zome in water 0.3-0.9 mm thick, green, glabrous, internodes 0.9-4.3 cm long. Land leaves with terete erect pilose to glabrate petioles 1.1-14 cm long, 0.3-0.7 mm thick, leaflets 0.2-1.7 cm long, 0.1-1.6 cm wide, rounded-spatulate to

broadly cun?ate, sparsely pilose or glabrous above, densely pilose below; floating leaves with lax petioles 12.5-100 cm long, 0.1-0.8 mm thick, leaflets 0.5-2.6 cm

long, 0.5-2.9 cm wide, cun?ate to flabellate; hydropoten irregularly distributed.

Fertile leaves produced on land on short nodal shoots (rarely on main shoots),

bearing solitary sporocarps on erect to procumbent wiry peduncles 1.7-6.7 mm

long, 0.2-0.3 mm thick, attached at the petiole base or up to 3.8 mm above it, the

point of attachment often obscured by hairs. Sporocarps 2.4-5 mm long, 2.0-3.0 mm wide, 1.3-1.7 mm thick, nodding or less often perpendicular to the peduncle apex, ovate in lateral view, elliptical in cross section, often with conspicuous lateral ribs, gray-brown to brownish black, covered with acicular 4-5-celled verru cose hairs with spreading tips when young but soon glabrate; raphe 0.6-1.4 mm

long, inferior tooth 0.2 mm long, blunt, or absent, superior tooth 0.2 mm long or

absent; lateral veins of sporocarp 16-20, forking midway, sometimes anastomos




ing at tips. Sori 10-14 per sporocarp, attached to a sorophore with a free acute

tip, 12-24 microsporangia and 1-6 megasporangia per sorus. Microspores more

than 53 per sporangium, 60-80 [im in diameter; 3-4 spores per sporangium brown and misshapen, either ovoid and 30-40 |xm long, or globose and 70 juim in

diameter. Megaspores 550-650 |xm long, 460-580 [im wide, with an apical papilla 60-80 |xm long. Figs. 4c, 5g, 171, m.

Phenology. In Arizona, M. mollis bears sporocarps from May through Oc

tober, while in Mexico it bears them from March until December and perhaps all

year. In Argentina the species produces sporocarps in October.

Distribution. (Fig. 16). Widespread and locally common in temporary ponds and lakes on clay substrates at 1800-3500 m from northern Arizona and the Davis

Mountains of western Texas south through the western and southern highlands of

Mexico, and also on the Andean plateaus of northern Argentina. It is probable that sterile collections of Marsilea from high elevations from Colombia to Argen tina represent this species; only rarely is any other Marsilea (M. ancylopoda) found at elevations above 1500 m in South America. To call attention to the

presence of Marsilea in the Andes, these sterile collections are cited here follow

ing the citation of specimens for M. mollis.

Representative Specimens. U.S.A. Arizona: Cochise Co., S Arizona near Fort Huachuca, Lemmon 2896 (GH f). Coconino Co., Coconino Nat. Forest, about 8 mi S of Mormon Lake, Correll

& Correll 39452 (NY, LL; st); Flagstaff-Sedona road, 23 Jun 1919, Goodding s.n. (ASU f); Coconino

Forest, Sec. 34, T16N, R8E, Hill 241 (US st). Graham Co., West Peak Pinelano Mountains, 8 Oct

1967, Minckley s.n. (ASU f, G st, KANU st); 8 mi W of Bonita at jet of Oak Creek and High Creek in

mudflats of Hooker Ci?nega, Pultz 1814 (GH f). Navajo Co., NW Ft Apache, 1 mi NW Grasshopper, 2 May 1967, Scott s.n. (ASU f). Santa Cruz Co., charco S of Lochiel-Parker Canyon Lake road, about

3.5 mi NE of Lochiel, Niles 698 & Reese 87 (UC f). Texas: Jeff Davis Co., Limpia Canyon, 12 mi W

of Ft. Davis, Palmer 30975 (GH st, KANU st, MO st, US f).?Mexico. Aguascalientes: 2 km al E de

La Congoja, sobre el camino a San Jos? de Gracia, Rzedowski & McVaugh 882 (ENCB f, MICH f). Chiapas: near Rancho Nuevo, road to Huist?n, 1 km NE of Mex Hwy 190, Breedlove 8316 (CAS,

ENCB; st); N end of San Crist?bal de Las Casas, valley toward Chamula, Breedlove 37135 (CAS st); San Crist?bal, M?nch 83 (P st); near km 152 on Hwy 190 just W of San Francisco between Laguna

Larga and Ajasaxh, Murray & Johnson 1404 (MICH f). Chihuahua: plains near Cusihuiriachic,

Pringle 2007 (CM, G, M, MEXU, MO, NY, PH, TEX, UC; f). Distrito Federal: La Candelaria,

Pedregal de San Angel, Rzedowski 2190 (ENCB st). Durango: Coyotes Hacienda 63 road mi WSW of

C. Durango, Maysilles 7869 (MEXU st, MICH f, US f); vie. C. Durango, Apr-Nov 1896, Palmer 13

(F, MEXU, MO, NY; f). Jalisco: near Guadalajara, Pringle 2434 (CAS, CM, F, G, M, MEXU, MO,

NY, P, PH, UC, US; f); Pringle 2632 (NY f); Pringle 3122 (CAS, F, MICH, MO, MSC, NY, P, US; f); 6 Dec 1889, Pringle s.n. (CAS, M, MEXU, MO; f); ca 8.8 mi ESE of Tacubaya, Reeves R5789

(ASU f). M?xico: 3 km al S de Tepotzotl?n, Arregu?n 589 (ENCB f ); Laguna de Zumpango, Arregu?n 596 (ENCB f); Fassen 28419 (GH, NY, US; f); 1 km N de Chapingo, por la carretera Mexico-Tez

coco, Garc?a P. 987 (F, NY; f); 3.5 km al este de Texcoco en carretera a Apizaco, Koch 74196 (CAS f, CHAPA f, ENCB st, MEXU st). Michoac?n: Morelia, Cerros de San Miguel, 1911 [?], Ars?ne s.n.

(MEXU, US, st); Zenzenguaro, ca 2 km al E de P?tzcuaro, Elizondo & S?nchez FaI-3190 (ENCB st, MEXU st). Oaxaca: [near city of Oaxaca, fide Davis (1936)], 7 Jun 1894, Pringle s.n. (F f ). San Luis

Potos?: 18 km SE San Luis Potos?, Rollins & Tryon 58319 (GH, US, f); in paludosis prope San Luis

Potos?, Oct 1876, Schaffner s.n. (NY f ); Schaffner 6 (P f; st); ex convalli San Luis Potos?, Schaffner 90

(P st). Sonora: Ca??n de los Apaches, R?o de Bavispe region, Phillips 805 (MICH st). Veracruz:

arroyo cercano a San Jos? por la carretera de Tulancingo a Huayacocotla, Brigada Vegetaci?n Acu?t

ica 239 (MEXU st).?Argentina. Jujuy: Depto Yavi, Pueblo Viejo, Ruthsatz 260[5] (LP f ); Hwy 5, 5

km W of La Quiaca, Johnson 759 (MICH f ); Hwy 69, 21 km S of Cienequillas, Johnson 760 (MICH f ).

Sterile Andean Collections. Colombia. Cundinamarca: Mun. de Tocancip?, km 38 de la carret

era Central del Norte, Acosta-Arteaga 154 (COL, NY, U); 4 km E of Saocha, Barkley & Wrigley




38772 (GH); Fontib?n, Cordillera Oriental, Ewan 15607 (NO, US); alrededores de Chocont?, lomas cerca al puente, sobre el r?o Sisga, Murillo 506 (COL); 4 mi SW of Bogot?, Pennell 2327 (NY, US); Bogot?, autopista a Medell?n, junto al r?o Bogot?, Uribe Uribe 6063 (COL).?Ecuador. Imbabura:

Lago San Pablo at Espejo, Asplund 7243 (US); Lago San Pablo, Fagerlind & Wilson 1326 (MO, R); Prescott 261 (CAS).?Peru. Cajamarca: Cajamarca, M?ller & Gutte 27322 (USM). Cuzco: Prov.

Espinar, alrededores de Yauri, Vargas C. 013524 (GH). Huancavelica: Prov. Angaraes, 4 km W of

Huanta, Stork & Horton 10808 (F, G, K, UC, US). Jun?n: Huancayo, Kunkel 314 (B); Kunkel 422

(GH). Puno: shallow ponds toward Juliaca, Hill 562 (K); Titicaca towards Juliaca, Hill 563 (K).? Chile. Coquimbo: Depto Illapel, Pan.-Am. Hwy. entre Huentelauquen y Puerto Oscuro, Ricardi et al.

1705 (SI).?Argentina. Tucum?n: Depto Chicligasta, Estancia Santa Rosa, Venturi 9654 (US).

The relatively small nodding sporocarps bearing spreading hairs, lacking a

superior tooth, and attached to slender wiry penduncles render this species readily

recognizable. Marsilea mollis is difficult to distinguish from M. vestita (no. 10),

especially when sterile, but differs consistently from it in a number of subtle

characters: the leaflets of M. mollis are fairly symmetrical, while those of M.

vestita are usually asymmetrical, sometimes almost falcate, with one corner of the

leaflet often pointed (Fig. 5); the leaflets of M. mollis have hairs with spreading

tips, while the hair tips on M. vestita leaflets are usually appressed; in living

plants, the leaflets of M. mollis are slightly crisped, while those of M. vestita are

flat and somewhat ascending. The closest relative of M. mollis is M. oligospora, as shown by the shared

similarities of the trichomes and sporocarps. Both species largely occur on inter

mountain plateaus, with M. mollis occurring from the Colorado Plateau south, and M. oligospora occurring along the northern margin of the Great Basin.

Twentieth Century botanists have misapplied the name Marsilea mexicana A.

Braun (=M. ancylopoda, no. 6) to this species, which may be attributable to a

widely distributed collection, Pringle 2007, which bore a printed label identifying it as that species. This specimen has two characteristics that became accepted as

diagnostic for M. mexicana sensu auctt.: red streaks on the leaflets, and sporo

carps clustered on short branches. The red streaks (hydropoten) are phenomena of floating leaves in all species of Marsilea; the second condition, in which sporo

carps may persist on old condensed nodal shoots long after the associated leaves

have disintegrated, commonly occurs in marsileas that have sporocarps lasting for

several seasons through changes in water level. Reports of M. mexicana from the

Texas Gulf Coast by Correll and Johnston (1970) and Hill (1982) on the basis of these characters were thus in error; all specimens concerned were water forms of

M. vestita.

Braun (1871) included M. mexicana in a group of species that all had recurved

peduncles and sporocarps lacking superior teeth, a group that also included M.

ancylopoda, M. ernestii, M. berteroi, and M. mutica. The small size of the sporo

carps and the upright peduncle of the species that has since been called M.

mexicana, however, do not tally with Braun's description, and upon examination

of the type of M. mexicana at Kew I found that it was a specimen with all the

characteristics of M. ancylopoda.

Despite its separation from the Mexican center of the range, the shorter

peduncles, and the slightly smaller sporocarps, M. punae appears to be conspe cific with M. mollis, and I predict that additional collecting in the Andes will yield fertile specimens of M. mollis that match those from Mexico.




The first name applied to this species, Marsilea picta F?e, was not validly

published, because F?e (1857) indicated that the name was only provisional ("qui lui a valu le nom provisoire qui nous lui donnons"). The herbarium names Marsi

lea holtingiana, which occasionally appears in the literature (e.g., Hollick 1904), M. heterophylla, and M. petularia apply to this species.

9. Marsilea macropoda Engelmann ex A. Braun in Kunze, Amer. J. Sei., Ser. 2, 6: 88. 1848. Zaluzianskia macropus (A. Braun) Kuntze, Revis, gen. pi. 2:

823. 1891.?Type: U.S.A. Texas: swamps of the Guadalupe bottoms near

Victoria, Jun 1845, Lindheimer III 573 [field no. 394] (holotype: MO!; isotypes: B! BM! G! K! MO! PH! UC!).

Plants forming dense colonies or persisting as scattered rhizomes. Rhizome

0.6-1.3 mm thick, stout, reddish brown to black, somewhat sclerified, apically with reddish orange hairs, bearing well-developed, ascending nodal branches 3-8 mm long, nodal roots 0.1-0.7 mm thick, internodes 1.1-4.4 cm long; rhizomes in

water 0.6-0.8 mm thick, green to brown, glabrous, internodes 0.4-1.7 cm long. Land leaves with canaliculate, sparsely hairy petioles 4.9-39 cm long, 0.3-0.8 mm

thick, leaflets 0.9-3.5 cm long, 0.8-3.9 cm wide, often longer than wide, flabel

late, slightly hairy above, conspicuously white-hairy below, the abaxial hairs often

protruding to make the leaflets appear white-margined adaxially. Floating leaves

with terete, green to stramineous petioles 28-30 cm long, 0.4-0.6 mm thick, leaflets 1.1-2.3 cm long, 1.3-2.4 cm wide, obconic; hydropoten present, short

and irregularly distributed. Fertile leaves produced on land, bearing 1-4 sporo

carps 2-4.5 mm above the petiole base on ascending branched or unbranched

peduncles; unbranched peduncles and ultimate branches of branched peduncles 8-17 mm long, 0.4-0.5 mm thick, the divisions of the branched peduncle joined

by a common trunk 1-5 mm long. Sporocarps 6-9 mm long, 4.5-5.5 mm wide, 2 mm thick, elliptical to quadrate in lateral view, ovate to elliptical in cross section,

ascending, dark brown to black, covered with appressed hairs that are tan at the

base and hyaline at the tips and that are often matted and twisted, eventually glabrate; raphe 1.6-2.4 mm long, inferior tooth 0.4-0.5 mm long, blunt, superior tooth absent or present as a slightly raised area; sporocarp veins ca 25, forking

midway, anastomosing into ar?oles above the tips. Sori 19-23 per sporocarp attached to a sorophore with a free tip, ca 50 microsporangia and 6-15 megaspo

rangia per sorus. Microspores 48-59 per sporangium, 70-78 jxm in diameter; 4-5

spores per sporangium occasionally brown and one-half normal size. Megaspores 530-580 (xm long, 400-440 |xm wide, with an apical papilla 40-65 |xm long. Figs. 2a, c, 4e, 5a, 8c, 9b, 15a-d.

Phenology. If sufficient water is available and frosts do not occur, M. macropoda

probably grows all year; I have observed vigorous plants in southern Texas in De

cember, and plants in the greenhouse in Michigan did not exhibit a dormancy pe riod. Some herbarium specimens collected in February and March, however, show new growth emerging from old rhizomes, so that the plants appear to be facultatively perennial. Sporocarp production occurs from February through November.

Distribution. (Figs. 18, 19). The range of M. macropoda is centered in south ern Texas, but the species also occurs north along the coast to Jackson County




and inland as far north as Brown County. It extends south into northern Coahu

ila, Nuevo Le?n, and Tamaulipas in Mexico, with an outlier near Jacala, Hidalgo. The collections from New Orleans, Louisiana, and Mobile, Alabama, probably

represent introductions, as they are from vacant lots in urban areas.

Marsilea macropoda occurs on pond edges, creek and river margins, and in

ditches from near sea level to 400 m in Coahuila and in Brown Co., Texas, and at

ca 1400 m in Hidalgo. In these habitats it usually occurs on waxy black clays of

pH 7-8, and less frequently on sandy soils.

Representative Specimens. U.S.A. Alabama: Mobile Co., Mobile, SE corner of Church St. and

Washington Ave., Burkhalter 5672 (NY st); S side of Old Mobile ca 0.5 mi S Government St., Krai

47120 (GH, US; f). Louisiana: Orleans Par., within City of New Orleans, vacant lot near corner of

Bienville and Salcedo Ave., Landry 7895 (NY f). Texas: Atascosa Co., Campbelton, Palmer 11245

(MO, NY, WS; st). Bexar Co., Parita Creek, Kosub Farm, 10 Jul 1939, Parks s.n. (TAES st). Brown

Co., 4 mi N of Brownwood, Stanford & Blassingame 1236 (UC f). Caldwell Co., along Hwy 183, 2.5

mi E of Hwy 90-183 jet in Luling, Johnson 691 (MICH f ). Cameron Co., about 2 mi S of San Benito,

Correll & Johnston 17918 (GH, LL, NY; f ); 2 mi NW of Laguna Vista, Crutchfield 1257 (LL, NY; f ); F.R. #510, 4.4 mi NW of Port Isabel, Crutchfield 2996 (LL, NY; f ); 1 mi W of Rio Hondo, Gould &

Hycka 8147 (TEX, UC; f); Brownsville, Tracy 9416 (GH, MO, NY; f); near Southmost, Webster &

Wilbur 3052 (G, MICH, NY, US; f). Calhoun Co., on route #35 between Green Lake and Tivoli,

Correll & Johnston 17525 (GH, LL, NY, UC; f). De Witt Co., along Guadalupe River SW of Cuero,

Correll 26835 (TEX st). Dimmit Co., Turkey Creek S of Crystal City, Muenscher & Winne 16506

(MSC, TEX, UC; f). Duval Co., San Diego, Croft 121 (MICH, NY; f). Frio Co., 7 mi N Dilley, Frio

State Park, Waterfall 13182 (F f). Goliad Co., McNamara Ranch, bend of San Antonio River, N side

of Hwy 59, Hill5520 (NY st). Gonzales Co., Ottine Swamp, Cory 18110 (GH f); Palmetto State Park, 15 Apr 1939, Tharp s.n. (MICH, MO, TEX; f). Guadalupe Co., Wixson's Creek, 1867, Lincecum s.n.

(MO f). Hidalgo Co., El Progresso near Weslaco, Clover 18 (MICH, NY, TEX; st); West Pond, Santa

Ana National Wildlife Refuge, Correll & Johnston 18017 (LL f); Military Road south at Donna,

Soxman 218 (TEX f, US st); Dona [Donna], Tracy 9142a (BM, F, G, GH, MO, NY, PH, TAES, US;

f). Jackson Co., Lavaca River, 29 Aug 1941, Tharp s.n. (GH, UC; f). Jim Wells Co., under bridge over Nueces River, just S of dam at Mathis, Reese 3347 (GH, SMS; st). Karnes Co., crossing San

Antonio River, Sep 1939, Parks s.n. (TAES st). La Salle Co., Interstate 35 bridge over Nueces River

on SW edge of Cotulla, 24 Jun 1982, Taylor & Mahler s.n. (NY f ). Live Oak Co., Nueces River 2 mi S

of Three Rivers, 22 Apr 1934, Wherry s.n. (PH f). MacMullen Co., 6 mi W of Tilden, Wolcott &

Barkley 16T307 (TEX, US; f). Maverick Co., Eagle Pass, May 1883, Havard s.n. (US f); Elm Creek

mouth, Eagle Pass, Schott 1929 (F, MO, US; st). Medina Co., Seco Creek just W of D'Hanis, Correll

& Ogden 25344 (C, ENCB, GH, NY, TEX, UC; f). Nueces Co., Corpus Christi, Penneil 10320a (NY,

PH; f). San Patricio Co., Welder Wildlife Refuge NE of Sinton, Johnson 718 (MICH st); Portland

Gregory, Tharp 5556 (MICH, PH, TEX, US; f). Starr Co., along Arroyo Los Olmos just E of Rio

Grande City, Correll 32314 (GH, LL, S, UC; f). Travis Co., Shoal Creek, Austin, 15 Apr 1901, Long s.n. (GH, MO, NY, TAES, TEX; f); Austin, Colorado River floodplain, 11 Mar 1928, Tharp s.n. (B,

NY, PH, US; f). Uvalde Co., Leona Water Hole, Cory 45355 (GH, TAES; f); Cory 49356 (LL f)

[Real Co.?]; Uvalde, Palmer 13350 (B, MO, US; st). Webb Co., about 11 mi NE of Laredo, route

#59, Correll 19756 (ENCB, GH, LL, MO, NY, UC; f). Wilson Co., Southerland Springs, Palmer

10803 (DS, MO, S; f). Zavalla Co. [Medina Co.?], between Moore and Devine, Palmer 33856

(MICH, MO, NY; f). County unknown, Wright 812 (GH f); Wright 2111 (MO, NY, PH, US; f).? Mexico. Coahuila: Rancho Agua Buena, 43 mi N of Monclova, Gould 6405 (CAS, MICH, TAES,

TEX, UC, WS; f). Hidalgo: Jacala, Edwards 789 (CAS, F, MO, TEX; st); Fisher 3798 (F f, GH st,

MICH st, RM f). Nuevo Le?n: R?o San Juan outside China, Barkley 14344 (ENCB f, F st, GH st,

MO f, NY f, TEX f, UC st); by stream 30 mi SW of Nuevo Laredo, Stern et al. 17 (F, TEX, US; f); Tamaulipas: Hacienda Santa En Gracia, Chase 7607 (F f ); on federal route 97, ca 5 mi S of Reynosa, Harriman 11408 (NY f); 14 mi N of R?o Carrizal on Mexico 180, Haynes 5440 (MICH f); near

Matamoros, Pringle 1975 (BM, F, G, K, LL, M, MO, MSC, NY, P, PH, S, UC, US; f); 78 mi E

Ciudad Victoria, bank of R?o Soto la Marina W of town, Ward 7755 (MICH f ).




The combination of large size, broad leaflets bordered by white spreading abaxial hairs, and sporocarps on long peduncles and lacking a superior tooth

usually serve to separate M. macropoda from sympatric Marsilea taxa. Sterile

specimens of M. macropoda that have leaves that are small and less hairy, thus

resembling M. vestita, can be identified by the stout sclerified rhizomes and stout

roots. Marsilea macropoda x vestita has broad hairy leaflets, but its sporocarps have a distinct superior tooth and are less strongly ascending.

Braun (1871) placed M. macropoda with M. quadrifolia and M. brownii (=M.

muticd) in one of his three major subdivisions of the genus because of its

branched peduncle. I consider the species to be more appropriately placed with

other North American taxa, on the basis of its large sporocarps with many (19

23) sori, conspicuous hairiness, lack of internodal roots, and production of xan

thone glycosides. Braun chose the epithet macropoda for his original description of the species,

a form of the epithet that was provisionally applied by Engelmann to the Lind

heimer collection. In all his later works, however, Braun used the form macropus. As there do not seem to be grammatical grounds for making the alteration, I concur with other authors who have adopted the original form of the epithet.

10. Marsilea vestita Hooker & Greville, Icon, filie. 2: t. 159. 1830. Zaluzianskia

vestita (Hooker & Greville) Kuntze, Revis, gen. pi. 2: 823. 1891.?Type:

U.S.A. Columbia River, Scouler 338 (lectotype, here designated: K!;

isolectotypes: GH! NY!).

Rhizome 0.4-0.6 mm thick, green or light brown to black, covered with

white or fulvous hairs at the apices, bearing well-developed short nodal shoots, nodal roots 0.1-0.3 mm thick, internodes 1.3-5.0 cm long. Land leaves with

canaliculate to terete petioles 2.0-19.5 cm long, 0.2-0.5 mm thick. Fertile leaves

produced on either long or short shoots, bearing solitary sporocarps at or up to

3 mm above the base on erect unbranched peduncles. Sporocarps nearly orbicu

lar to elliptical in lateral view, elliptical or ovate in cross section, perpendicular to peduncle apex, slightly nodding or slightly ascending, olive-yellow, brown,

black, covered with long hairs with spreading hyaline tips or with short ap

pressed hairs, often appearing speckled from brown or purple scars left by hairs that have fallen off; inferior tooth 0.3-0.6 mm long, blunt; sporocarp veins ca

20, forking midway, anastomosing at the tips or not at all. Sori 14-22 per

sporocarp.

Phenology. North of Mexico, M. vestita produces sporocarps from April through October, while in Mexico sporocarps are produced throughout the year.

Plants from western Montana and central California, grown in a greenhouse in

Michigan, showed reduced vigor or death of most leaves in November or Decem ber but produced new growth in February and March. Plants of M. vestita from

south-central Texas grown alongside these, however, showed no signs of dor

mancy during the winter.

Habitat. Marsilea vestita occupies a diversity of wet habitats, including pond and lake edges, arroyos, ditches, prairie marshes, river floodplains, old buffalo

wallows, and wet pastures, in both sandy and clayey soils. Common macrophyte associates include species of Ammannia, Heteranthera, Ludwigia, Panicum, Poly




gonum, and Sagittaria, but plants may persist in sites with species of non-aquatic

genera, such as Artemisia, Chrysothamnus, and Dalea.

Marsilea vestita comprises two subspecies, one of wide distribution (Fig. 18) and the other restricted to a small area in central Texas (Fig. 19). This species shares characters with several species in sect. Nodorhizae, and it is thus difficult

to identify a close relative. Marsilea vestita shares the multiseriate sporocarp

epidermis and production of C-glycosylxanthones with M. macropoda, a sporo

carp with a conspicuous superior tooth with M. nashii and M. villosa, and hairy adaxial surfaces of the leaflets with M. macropoda, M. oligospora, and M. mollis.

Hooker and Greville cited specimens collected by both Douglas and Scouler

in their description of M. vestita; because the Scouler collection at K most closely matches the plate and original description, I have chosen it as the lectotype.

Braun (1871) used varietal names to refer to several collections belonging to

this species. For one of these, M. vestita var. minima, he provided enough infor

mation to constitute a diagnosis. The other two, M. uncinata var. texana and M.

mucronata var. antrorsa, are nomina nuda and have not been validated.

10a. Marsilea vestita subsp. vestita.

Marsilea uncinata A. Braun ex A. Braun, Amer. J. Sei., ser. 2, 3: 55. 1847.

Marsilea vestita var. uncinata (A. Braun) Baker, J. Bot. 24: 279. 1886.? Type: U.S.A. Arkansas: on the margin of small swamps in the deep bottom woods on the Arkansas River, not far below Little Rock, Jul

1835, Engelmann 33 (holotype: MO!; isotypes: K! M! MO!). Marsilea mucronata A. Braun, Amer. J. Sei., ser. 2, 3: 55. 1847. Marsilea

vestita var. mucronata (A. Braun) Baker, J. Bot. 24: 279. 1886.?Type:

U.S.A. [North Dakota]: in small exsiccated swamps near Devil's Lake, 24

Jul 1839, Geyer 71 (holotype: MO!; isotypes: K! NY!). Marsilea vestita var. minima A. Braun, Monatsber. K?nigl. Preuss. Akad.

Wiss. Berlin 1863: 424. 1864.?Type: U.S.A. New Mexico [actual locality near San Elizario, Texas], 1851-1852, Wright 2112 (holotype: location

unknown; isotypes: GH! MO! NY! UC!). Marsilea minuta E. Fournier, Bull. Soc. Bot. Fr. 27: 329. 1880, non Marsilea

minuta Linnaeus, 1771. Marsilea fournieri C. Christensen, Index filie.

418. 1906.?Type: Mexico. San Luis Potos?, Schaffner s.n. (holotype: location unknown; isotype: NY!).

Plants forming diffuse or dense colonies. Rhizome in water 0.5-0.7 mm thick,

green or brownish, glabrous, internodes 1.6-5.8 cm long. Leaflets of land leaves 0.4-1.9 cm long, 0.4-1.6 cm wide, spatulate to flabellate, asymmetrical, with

overlapping hairs adaxially and abaxially, with concave inner lateral margins and

entire or remotely denticulate terminal margins; floating leaves with lax petioles 6.5-35 cm long, 0.3-0.6 mm thick, leaflets 0.8-1.8 cm long, 0.8-1.5 cm wide, obovate to flabellate; hydropoten irregularly distributed or absent. Peduncles 1.5-25 mm long, 0.3-0.4 mm thick; petioles rarely with two sporocarps on a

bifurcate peduncle. Sporocarps (3.0-) 3.6-7.6 mm long, (2.0-) 3.1-6.5 mm wide, 1.5-2.0 mm thick; raphe 1.1-1.7 mm long, superior tooth 0.4-1.2 mm long, acute, often hooked at the apex. Sori each with 27-64 microsporangia and (2-) 9-15 megasporangia, attached to a sorophore with a free acute tip. Microspores




16-64 per sporangium, 65-80 |xm in diameter; if spores in low numbers in a

sporangium, then some brown, misshapen, and with a maximum dimension of

30-60 fim. Megaspores 450-515 |mm long, 320-400 jxm wide, with an apical

papilla 50-83 jxm long; often abortive in specimens from the southeastern limit of

the range. Figs. 2g, 3, 4b, 5c, f, 7a, 17g, h.

Distribution. (Fig. 18). Marsilea vestita subsp. vestita occurs from southern

British Columbia east to Saskatchewan and western Minnesota and south to Baja California, Zacatecas, San Luis Potos?, and Louisiana, with a disjunct station in

northern coastal Peru, at elevations from sea level to 2300 m. It is largely absent

from the intermountain region of the United States, where M. oligospora occurs, and from the northern Mexican highlands, where the range of M. mollis begins. Recent collections from Florida (e.g., Hall 414) are probably of introduced plants

(Ward & Hall 1976). Representative Specimens. Canada. Alberta: near Hand Hills, Macoun 3052 (BM f); Macoun

14208a (GH, US; f); Spur Creek, Macoun 14209 (GH, NY, S, US; f); Cypress Hills, 7 Aug 1879, Macoun s.n. (GH f ). British Columbia: 3 mi N of Vernon at Goose Lake, Colder & Savile 10140 (GH

st, NY f, US f); Indian Reservation, Kamloops, Macoun 14208 (CM st, GH f, NY f, US f). Saskatchewan: Moose Jaw, Macoun 14210 (GH, NY, S, US; st).?U.S.A. Arizona: Mohave Co.,

Signal Road, 15.1 mi E of U.S. 93, Lehto 12872a (ASU f, G f ). Pima Co., margins of Aguirre Lake on

Buenos Aires Ranch N of Sasabe, Haskell & Darrow2170 (US f). Pinal Co., Pichaco Reservoir north

of Pichaco Mts, Pultz & Phillips 2573 (GH, MO, UC, US; f). Yavapai Co., Ash Fork, Griffiths 4734

(MO f). Arkansas: Arkansas Co., Arkansas Post State Park, Demaree 21061 (CAS, GH, MO, NY,

PH, UC; st). Bradley Co., Warren, Demaree 19442 (MO f). Faulkner Co., on Arkansas River 1.5 mi

S of Toad Suck Lock & Dam, Johnson 687 (MICH f). County unknown, 1834, Beyrich s.n. (MO f). California: Butte Co., Chico-Hamilton road, 6 mi from Chico, Heller 11633 (CAS, DS, F, G, GH,

MO, PENN, PH, UC, US; f). Humboldt Co., Orleans, Aug 1943, Pollard s.n. (CAS f). Imperial Co.,

Colorado River, Bard, Goodding 43-14 (CAS, GH, NY; f). Kern Co., Lake Isabella, about 5 mi S of

Kernville, Howell 47460 (CAS, NY, US; f ); Kern River Canyon, about 1 mi W of Dougherty Creek

and 5 mi SW of Democrat Springs, Howell 38683 (CAS f, GH st, RM st, US f). Los Angeles Co.,

Boquet Reservoir at east end, Raven 16748 (BM, CAS, GH, RM; f). Madera Co., Bass Lake, Storer

390 (MICH, US; f). Orange Co., Costa Mesa, 12 Apr 1935, Haupt s.n. (CAS, DS, MICH, MO, NO,

NY, RM, TEX, UC, US; f). Riverside Co., Mystic Lake, near Moreno, Munz & Johnston 5154 (CAS,

DS, GH, RM, UC, US; f); Riverside, Pringle 2729 (CAS, DS, F, G, GH, M, MO, NY, PENN, PH,

US; f). San Bernardino Co., Bear Valley, San Bernardino Mts, Peirson 10674 (DS, NO, UC; f); Barton Flats, San Bernardino Mts, Santa Ana River, Wheeler 1235 (GH, NO, Z; f). San Diego Co.,

Cuyamaca Lake, Abrams 3852 (BM, CAS, F, G, GH, K, MO, NY, PH, UC, US, Z; f); 7 Jul 1894,

Brandegee s.n. (NY, RM; f); Sweetwater, Sep 1884, Orcutt s.n. (GH f, UC f); Cuyamaca Lake,

Wiggins 2119 (CAS, MICH; f). Santa Barbara Co., Santa Barbara, Nuttall s.n. (K f). Siskiyou Co.,

Siskiyou Mts, Shasta River 2 mi below Yreka Creek, Wheeler 3323 (CAS f). Stanislaus Co., near

Modesto Reservoir, Raven 16601 (BM, CAS, DS, GH, NY, RM, UC; f). Sutter Co., Dean Ranch,

Sutter Buttes, W of Marysville, Ahart 4404 (MICH, MSC; f). Tulare Co., 8 mi N of Visalia, Baciga

lupi et al. 2498 (CAS f, GH f, UC f, US st); near Visalia, Coville & Funston 1275 (C, CAS, GH, K,

NY, US; f); Tulare, Michener & Bioletti 14 (MICH, MO, UC; f); between Tulare and Tulare Lake,

Palmer 2766 (DS, NY, US; f). Ventura Co., Ojai Valley, Mirror Lake, Keifer 498 (KANU, UC; f); 28

Jun 1952, Pollard s.n. (CAS st, DS st, G st, GH f, TEX f, UC f, WS st). Colorado: Baca Co., 6 mi

W, 18 mi S of Pritchett, Stephens 54289 (KANU, NY; f). Boulder Co., E of Boulder, Bethel ?tal. 3994

(C, CAS, CM, F, JEPS, K, MICH, MO, NY, RM, S, TEX, WS; f except S); Bohn Lake, NE base of

Table Mtn, 11 mi N of Boulder, Weber 13368 (CAS, M, TEX; f). Elbert Co., NE of Kiowa, summer

1943, Thorp s.n. (NO f). El Paso Co., nr Colorado Springs along Farmers Highway, Sep 1935,

Penland s.n. (PH f). Larimer Co., Fort Collins, 17 Jun 1893, Cowen s.n. (MICH st, MO st, RM f). Lincoln Co., S9, T15S, R57W, Ownbey 1334 (CAS, GH, MO, NY, RM, UC, WS; f). Phillips Co., 5.5

mi S Huxton, Stephens 62504 (KANU f). Saguache Co., Saguache, Wolf 174 (F, US; f). Weld Co.,

Coleman, Johnston 1039 (RM f); New Windsor, Osterhout 4142 (NY, RM; f). Yuma Co., S edge of

Yuma, Stephens 62516 (KANU, NY; f). Florida: Franklin Co., Apalachicola W of Market St. and N




of "F" Street, Leonard 8495 (MICH f). Hillsborough Co., Ruskin, Hall 414 (US, NY, PH; st); 6 May

1979, Darling s.n. (US f). Idaho: Ada Co., NE side of Boise River near old Strawberry Glen Bridge and airport, west end of Boise, Enter 3958 (NY f). Franklin Co., 2 mi N Oxford, Maguire3173 (RM,

UC; f). Gem Co., 12 mi W Emmett, Christ 8528 (NY f). Kootenai Co., Jim 1887, Sandberg s.n. (F f). Nez Perce Co., island in mouth of Clearwater, 12 Oct 1924, Ridout s.n. (WS f); T32N, R5W, Lime

Point, St. John 4371 (WS f). Iowa: Lyon Co., NW corner, Jul 1899, Shimek s.n. (GH st). Kansas:

Barber Co., 4 mi E of Isabel, McGregor 10701 (KANU f ). Barton Co., 1 mi SW Great Bend, Stephens & Brooks 357 (CAS, GH, KANU, NY, UC, US; f). Chase Co., 1 mi SW Elmdale, McGregor 3937

(KANU f). Cherokee Co., 5 mi W, 2 mi N Melrose, Neosho River, Kolstad & Harms 1581 (KANU,

NY; f). Clark Co., 1 mi SW Minneola, McGregor 4024 (KANU f). Edwards Co., 6 mi S, 6 mi E of

Kinsley, Stephens 84867 (GH, KANU; f). Ellis Co., near Hays, Runyon 112 (GH, MICH; f). Finney

Co., 1 mi E Garden City, McGregor3991 (KANU f). Ford Co., 7 mi NE Dodge City, McGregor3972

(KANU f). Harper Co., 3 mi N Danville, Stephens 84614 (GH, KANU; f). Harvey Co., 3.5 mi N

Burrton, Stephens 34762 (KANU f). Haskell Co., 0.5 mi E of Sublette, H?user 2197 (KANU f).

Hodgeman Co., 5 mi NE Grayling, McGregor 3962 (KANU f). Kingman Co., 6 mi NW Kingman,

McGregor 2230 (KANU f). Kiowa Co., 3 mi W Haviland, 17 Aug 1950, Fearing & Latham s.n. (GH,

KANU; f). Lane Co., 4 mi S Dighton, McGregor 3278 (KANU f). Meade Co., 19 Va mi S, 1.5 mi E

Meade, Brooks 13292 (KANU f ). Neosho Co., Erie golf course, Holland 1993 (KANU f ). Pratt Co., 4

mi E Iuka, Barker 1809 (KANU f). Reno Co., 2 mi E, 3.3 mi N Quivira National Wildlife Refuge

Office, Magrath & Weedon 5760 (KANU f). Rooks Co., Rockport, 28 Jul 1886, Bartholomew s.n.

(MO f). Saline Co., 2 mi W, 2 mi N Salina P. O., Humfeld 445 (KANU, NY; f). Sedgwick Co., 3 mi

N Wichita, McGregor 4047 (KANU f). Seward Co., 2 mi NW Kismet, McGregor 4010 (KANU f); N

edge of Liberal city park, Stephens 84216 (GH, KANU; f). Trego Co., l3/4 mi N, 3.5 mi E Voda, Caldwell s.n. (KANU f). Louisiana: East Baton Rouge Par., just E of Mississippi River near River

Road, Baton Rouge, Pias 4088 (NLU f). Orleans Par., Mississippi River, New Orleans, Cocks s.n.

(NO f, st, NY f ). Ouachita Par., N of Horseshoe Lake, W of La 553, Thomas 29583 (UC f ). Rapides

Par., vicinity of Alexandria, Ball 492 (F, GH, MO, US; f). St. Charles Par., Bonnet Carre spillway, Montz 5190 (NO f). Minnesota: Norman Co., near Gary, Jul 1880, Dudley s.n. (GH st). Pipestone

Co., Vi mi N of Pipestone, Moore & Moore 10550 (F, KANU, NY, S, TEX, UC, WS; f). Polk Co., 10

mi N Crookston, Nielsen 3570 (NY f). Rock Co., 4 mi NNW of Luverne, Moore & Tryon 17578

(KANU f, NY st, UC f, WS f). Steams Co., Roscoe, Nielsen 3607 (CAS f). Montana: Custer Co., Sec. 4, T6N, R43E, dry lake, Pasture J, Woolfolk 79 (RM f). Lake Co., Kicking Horse Reservoir 20

mi S of Flathead Lake, 30 Jun 1950, Blanchard s.n. (MICH f ); 3 mi W Ravalli, Rose 758 (US f ). Lake

or Sanders Co., W of Benson Ranch, NW Ravalli, Barkley 2554 (GH, K, NY; f). Nebraska: Chase

Co., near Lamar, Tolstead 41570 (MO, NO; f). Clay Co., 3 mi N, 1 mi W of Ong state refuge, Churchill 2300 (MO, NY; st); Vi mi E, 5 mi N Edgar, Churchill 6585 (KANU, MO, NLU, NY; f ). Custer Co., 6.5 mi SE Anselmo, Stephens 25181 (CAS, KANU; f). Dawes Co., Chadron, 27 Jun 1871, Bates s.n. (NY f). Fillmore Co., 1 mi W Fairmont, Kiener 17144 (GH, MO; f). Gosper Co., 1 mi NW

Bertrand, Kiener 19386 (MO, TEX; f). Hall Co., 4.5 mi N Hansen, Brooks 465 (KANU f). Hayes

Co., 6 mi SE of Hayes Center, Tolstead 41569 (MO, NO, U, UC; f). Kearney Co., Minden, 17 Aug

1932, Hapeman s.n. (PH f); Rydberg 6604 (NY st, RM f). Wheeler Co., 4 mi N Bartlett, Stephens 24286 (CAS, KANU; f). York Co., S side of York, Krai 28908 (C, KANU, MICH, PH; f). Nevada:

Douglas Co., W of "Reservoir" NE of Minden, Reveal 2820 (CAS, MO, NY, US; f). Elko Co., Humboldt River, Carlin, Holmgren 1696 (NY f ); Goose Creek Valley, Watson 1372 (NY f). Humboldt

Co., Winnemucca, 1 Sep 1897, Hillman s.n. (DS f). Washoe Co., Little Washoe Lake near Washoe

City, Howell 52202 (CAS f ); Truckee Meadows, sloughs along Kleppe Lane, E of Sparks, Tiehm 3966

(NY f). New Mexico: Eddy Co., Queen, Standley 40706 (GH, US; f); vicinity of Queen, 2 Aug 1909, Wooton s.n. (US f, st). Lea Co., S side of Hwy 62 & 180, about 10 mi W of Hobbs, Correll & Correll

36062 (LL, NY; f). Roosevelt Co., 10.5 mi E Elida, Stephens 80149 (KANU f). San Miguel Co., Las

Vegas, Begoso canyon, Ars?ne 18763 (F, US; f ); 4 mi SE Cline's Corner along highway to Vaughn, 2

Aug 1937, Goodding s.n. (US f). Sierra Co., just W of Elephant Butte, Correll & Correll33044 (ASU, LL, NY; f ); below Elephant Butte Dam at U.S. Fish Hatchery, Crutchfield 168 (LL f, NY st). Socorro

Co., Bosque del Apache Refuge, Fleetwood 2030 (US f). Taos Co., Cerros de Taos, 0.2 mi S of US

Hwy 64, about 18 mi NW of Taos, Holmgren & Holmgren 7297 (ASU, NY; f). North Dakota:

Adams Co., 7 mi E, 5 mi N Hettinger, Stephens 50100 (KANU f). Barnes Co., Valley City, Stevens

1223 (UC, US; f). Burleigh Co., 2.5 mi S Menoken, Brooks 1516 (GH f). Dickey Co., 7 mi N

Ellendale, Stephens 61406 (KANU f ). Foster Co., Carrington, 21 Aug 1935, Stevens & Kluender s.n.




(CM, F, UC; f). McLean Co., Butte, 10 Sep 1905, Lunells.n. (CAS, G, GH, K, M, MO, NY, PENN,

PH, RM, UC; f). Mountrail Co., Stanley, 20 Aug 1915, Stevens s.n. (F, GH, NO, RM; f). Stark Co.,

Dickinson, 15 Aug 1908, Holgate s.n. (NY, US; f). Oklahoma: Cleveland Co., 1 mi S Norman,

Barkley 1190 (MO, OKL, US; f). Cotton Co., 8 mi W and 4 N of Randlette, Waterfall 8359 (OKL, PH; f). Creek Co., Sapulpa, Bush 838 (GH, MICH, MO, NY, OKL, UC, US; f). Dewey Co., 4 mi W

of Vici, Waterfall 7122 (PH f). Ellis Co., US Hwy 282, 7.8 mi N of Packsaddle Bridge, Goodman &

Lawson 8422 (G, KANU, OKL; f). Garvin Co., 13 mi W & 1 S of Pauls Valley, Waterfall 5591 (NY,

OKL, OKLA; f). Grant Co., 15 mi W Medford, Stephens 71200 (KANU f). Greer Co., 1 mi E

Plainview, Higgins 7672 (NY f). Harper Co., 12 mi W Buffalo, Stephens 71477 (KANU f). Johnston

Co., nr Mannsville Griffith 3465 (DUR, MO, OKL; f). Kay Co., 6.5 mi W Blackwell, Stephens 76783

(KANU, OKL; f). Love Co., spillway at Lake Murray, Correll & Correll40036 (ASU, NY, TEX; f).

Major Co., 11 mi E Orienta, Stephens 27125 (KANU f). Marshall Co., Lake Texoma 1 mi W of U.

Okla. Biol. Station, Goodman 6674 (GH, KANU, OKL, OKLA, TEX, UC; f). McClain Co., 5 mi N

Washington, 26 Apr 1934, Wherry s.n. (PH f). Murray Co., Buckhorn Springs 6 mi S of Sulphur,

Crutchfield 1787 (NY, TEX; f). Osage Co., Sec. 8, T27N, R6E, 30 May 1922, Greene s.n. (US f).

Payne Co., Stillwater, 29 Aug 1895, Blankinship s.n. (GH f, st, MO st, US f). Texas Co., nr Hooker,

Pony Creek, Stevens 383 (CAS, GH, K, MO, OKL, OKLA, US; f). Washington Co., 2 mi W, 2 N, Vi

W Copan, Stephens 76963 (KANU f). Woods Co., near Avard, Stevens 562 (CAS, K, MO, OKL,

OKLA, US; f). Oregon: Clackamas Co., NE of Portland, Wiegand 33 (F f). Curry Co., 4 mi N

Agness, Rogue River at Cherry Flat, Baker 5653 (UC f). Hood River Co., Columbia River bottoms,

Henderson 530 (MO f ). Klamath Co., near mouth of Williamson River, Leiberg 726 (MO f, US f, WS

st). Lake Co., N shore Silver Lake, 7 mi E of town of Silver Lake, Steward 7250 (ASU, CAS, GH,

NY, PH, U; f). Multnomah Co., Sauvie's Island, Sep 1880, Howell s.n. (CAS, CM, F, G, GH, MO,

NY, PENN, US; f); Hayden Island near Oregon side of the Interstate Bridge, 16 Sep 1927, Thompson s.n. (NO, PENN, PH; f). Umatilla Co., near Umatilla, May 1939, Zivney s.n. (KANU f, WS st).

Wasco Co., near The Dalles of the Columbia River, Hall 697 (BM, CM, F, G, GH, MO, NY, UC,

US; f ); The Dalles of the Columbia, 11 Oct 1881, Pringle s.n. (F, G, NY, PH; f ); Columbia River near

the mouth of the Deschutes River, Thompson 11881 (CAS, MO, NY, PH, UC; f ). County unknown,

Columbia [River], Douglas s.n. (K f). South Dakota: Aurora Co., 1.8 mi E of Plankington, Rt 16,

Roadside Park, 5 Sep 1962, Liester et al. s.n. (ASU f). Brookings Co., Brookings, Sep 1893, Williams

s.n. (MO f, NY f, st, RM f). Brown Co., Aberdeen, Aug 1896, Griffiths s.n. (CM, F, NO, RM, US;

f). Custer Co., between Buffalo Gap and Fairburn, Hayward2576 (F f, st, RM f). Harding Co., Little

Missouri Valley, 12 mi N Camp Crook, Visher 19 (F, RM; f). Kingsbury Co., Iroquois, 1 Aug 1912,

Thornber s.n. (UC f). Mellette Co., 4 mi E Wood, Stephens 49273 (KANU f). Pennington Co., 5 mi S

Scenic, Hayward 559 (F, NY; f). Sanborn Co., 3 mi E, 12.5 mi N Forestburg, Stephens 48801 (ENCB,

KANU; f). Shannon Co., Pine Ridge Reservation, Visher 2142 (F, NY; f). Texas: Bell Co., near

Temple at Bird Creek, Wolff 2252 (MSC, TAES; f). Bexar Co., Leon Springs, 5 Jun 1911, Clemens &

Clemens s.n. [374?] (CAS, MO, RM; f ); near Elmendorf Lake, 4 Jul 1935, Metz s.n. (M, MICH; f ). Brazoria Co., Columbia, Bush 173 (GH f, K f, MO st, NY f, US f). Brazos Co., near Stone City, Palmer 13465 [124645?] (BM, F, [MICH], MO, RM, [US]; f). Caldwell Co., dry sink, prairie, Barkley 13130 (CAS, DS, GH, K, RM, TAES, TEX, UC, US; f). Carson Co., 2 mi E Panhandle, Stephens 82584 (KANU, NLU; f). Comal Co., bed of Cibolo River, Bracken, Groth 154 (CAS, F, GH, K, US;

f); Comanche Spring, New Braunfels, etc., Lindheimer 1282 [=125] (BM, C, F, GH, K, MO, NY,

PH, TEX, UC, US; f); Lindheimer 1283 [=590] (BM, C, F, G, GH, K, M, MO, NY, PENN, PH, TEX, UC, US; f). Concho Co., 2 mi E of Vick on US Hwy 87 between Eden and Vick at Roadside

Park, Crutchfield 2 (GH, LL, S, UC; f). Dallas Co., Dallas, Hall 861 (BM, GH, K, MO, US; f); swamps near Dallas, June, Reverchon s.n. (Curtiss, N. Am. Plants 3819) (BM, CM, F, G, GH, K, M,

MICH, MO, NY, PH; f); Bachman's Lake, Soxman 106-a (US f). Deaf Smith Co., 5 mi SW of

Hereford, Waller 1258 (ASU f, ENCB st, TAES st). Duval Co., 7 mi S of San Diego toward

Benavides, Correll & Johnston 25500 (GH, TEX; f). Ector Co., N edge of Odessa, Correll 32766

(ASU, LL, NY; f). El Paso Co., Hueco Tanks, Hueco Mountains, Waterfall6621 (GH, MO, NY; f).

Gray Co., 3 Vi mi S Pampa, Stephens 71856 (KANU f). Hansford Co., 3 mi W of Spearman, Correll &

Ogden 28362 (F st, LL st, MO f, UC st). Hartley Co., 1 mi SE Hartley, Stephens 75384 (KANU, NY; f ). Kaufman Co., 2 mi N of Mabank, Correll et al. 28069 (F, LL; f). Kenedy Co., Riviera, Tharp 4270

(TEX f, US f). Lamb Co., Littlefield, Laguna Park, 3 Jan 1982, Marshall s.n. (MICH f). Lipscomb

Co., just over county line from Hemphill Co. off FM 305, Crutchfield3536 (LL, NY; f). Llano Co., on

the Llano River 4 mi E of Llano, Seigler et al. 1545 (TEX f). Lynn Co., S of Tahoka, Tharp 4271




(TEX, US; f). Nueces Co., Rt 77, 2 mi S of Driscoll, Hall 2738 (NO f). Ochiltree Co., 3.5 mi S

Perryton, Stephens 71609 (KANU, NY; f ). Schleicher Co., 26 mi W of Eldorado, Parks & Cory 32683

(TAES f). Taylor Co., 10 mi SW of View, Tolstead 7221 (MICH, TAES; f). Travis Co., along Onion

Creek, 8.5 mi S of Colorado River in Austin, Correll & Correll 29940 (LL, MO, UC; f ); Austin, banks

of the Colorado River, Hall 860 (BM, F, G, GH, K, MO, NY, US; f); Manchaca, Palmer 12148 (GH,

MO, US; f). Val Verde Co., along banks of Devil's River, Correll & Wasshausen 27784 (F, LL, NY;

f). Wharton Co., Pierce, Tracy 9137 (BM, F, G, GH, MO, NY, PENN, TAES, TEX, US; f except

G). County unknown, in the pools in the mountains between the Cibolo and Upper Guadalupe, Lindheimer IV 746 [field no. 404] (BM, G, GH, K, M, MO, PENN, PH, S, UC; f ). Utah: Salt Lake

Co., 5th W, 23rd S, Flowers 3247 (G, NY; f). Washington: Asotin Co., Snake River just above

Asotin, Sharsmith 4047 (CAS f, DS f, S st, UC st). Franklin Co., Sacajawea State Park, along strand

of Columbia River just below confluence of Snake River, Raven 10347 (CAS f). Grant Co., Gopher

Island, Columbia River, E of Ginkgo Petrified Forest State Park, Smith 218 (UC, WS; f). Kittatas

Co., Sentinel Bluffs, Craig's Ferry, Cotton 1347 (GH, MO, RM, US; f); along Columbia River near

Vantage Ferry, Hitchcock & Muhlick 13728 (CAS f, DS f, GH f, MO st, PH st, RM st, TEX st, UC st, WS f); bank of Columbia River opposite the Wenatchee, Watson 470 (GH, PH; f). Klickitat Co.,

low bottomlands of the Columbia River, Oct-Nov 1883, Suksdorf s.n. [6251] (BM, CAS, DS, F, G,

GH, NY, PH, UC, US, WS; f); Columbus, Suksdorf 2620 (NY, WS; f). Okanagan Co., Leader Lake, 4 mi W of Okanagan, 28 Jul 1949, Yocom s.n. (WS f). Walla Walla Co., Walla Walla, Parry s.n. (GH

f). Whitman Co., sandy bank of the Snake River at Wawawai, 15 Oct 1939, Ownbey & Ownbey s.n.

(CAS, CM, DS, GH, NY, RM, UC, WS; f); Almota 9 Sep 1896, Piper s.n. (WS f). Wyoming:

Campbell Co., 41 mi N Gillette, Stephens 23846 (KANU f). Laramie Co., 3 mi W of Cheyenne, Dorn

3176 (RM f).?Mexico. Baja California Sur: San Jorge, 18 Mar 1889, Brandegee s.n. (CAS, UC; f); San Jos? del Cabo, 16 Oct 1899, Brandegee s.n. (NY f, RM f, UC f, US st); beside carretera from

Loreto to Villa Constituci?n, Carter 5934 (BM, MEXU, UC; f ); La Laguna, on plateau E of La Paz, Carter & Kellogg 3227 (GH f, MEXU f, MICH f, UC st); Sierra de la Giganta, Laguna de Notr?, north base of Cuesta de Chenque, ca 20 km S of Loreto on road to Puerto Escondido, Carter & Moran

5394 (BM, CAS, G, GH, MEXU, MICH, MO, NY, TEX, US; f); 19 mi W of Canipole, Shreve 7116

(DS, F, GH, MICH, MO; f); 20 mi S of Calmalli, Wiggins 5422 (CAS, DS, GH, MICH, MO, NY, RM, UC, US; f); 15.5 mi S of El Arco, Wiggins 15162 (CAS, ENCB, GH, MEXU, TEX, UC; f). Coahuila: vie. Torre?n, 13-20 Oct 1898, Palmer 467 (BM, G, K, MO, NY, UC; f); Cerro de

Cypriano [near Hacienda Movano (=Mohovano Ranch?) fide Sousa S?nchez 1969], Purpus 4525 (B,

BM, F, GH, MO, UC, US; st except UC). Durango: 24 km NE from Durango on road to Torre?n at

"Betania," Johnston et al. 11448 (LL f ). Nuevo Le?n: Rt 85, stream at La Gloria, Seigler et al. 1292

(TEX f ). San Luis Potos?: vicinity of San Luis Potos?, 1878, Palmer 1010 (F, K, MO, NY, PH, US; f );

prope San Luis Potos?, Schaffner 15 (CAS, F, MICH, NY, PH, US; f). Sonora: San Pedro, Hartman

893 (MO, UC, US; f ); 5 mi E of D?til [Atil] on road to Rancho San Ignacio, Wiggins 6101 (CAS, US; f); 2 mi NW Rancho San Carlos, ca 40 mi W of Hermosillo on road to Kino Bay, Wiggins & Rollins

181 (CAS st, MICH st, MO f, NY st, TEX f, UC st, US f). Zacatecas: near San Miguel, Jones 157

(GH, DS, MO, MSC, US; f).?Peru. Lambayeque: Chiclayo, 10-8-81, Le?n s.n. (MICH f).

Marsilea vestita subsp. vestita occupies the largest continuous range of any New World Marsilea, and exhibits regional variations in characters, such as length and abundance of hairs, size of sporocarps, width of leaflets, and length of sporo

carp peduncles. It is usually recognizable by the combination of relatively large sporocarps that are slightly nodding to slightly ascending, often on short stout

peduncles, a conspicuous superior tooth on the sporocarp, and relatively broad

leaflets with at least one concave lateral margin. The conspicuous superior tooth of the sporocarp and the angle of the sporocarp to the peduncle separate it from

M. oligospora. The appressed hairs and the large sporocarp with a superior tooth

distinguish M. vestita from M. mollisf which has spreading hairs and a small

sporocarp lacking a superior tooth.

Marsilea vestita subsp. vestita is widespread and variable; the taxa here placed




in synonymy are based on specimens that represent extremes of variation, but

which are interconnected morphologically by a fairly complete spectrum of inter

mediates. Marsilea uncinata was characterized as having a strongly curved supe rior tooth on the sporocarp, a flattened sporocarp nearly orbicular in shape,

peduncles that are longer than the sporocarp, and relatively few hairs on the

leaflets. Many collections of individuals with such characters have been made in

Louisiana, Arkansas, and eastern Texas. These characters are infrequent in M.

vestita in general, but most of them are also characters that are environmentally

plastic. Bhardwaja (1967) observed that peduncle length increased in M. minuta

under certain environmental conditions; similarly, I have found that sporocarps of

many species grown in pots in the greenhouse had longer peduncles when formed

in the crowded pots rather than on creeping rhizomes trailing out over the sides of

the pot. Leaves of plants grown in the greenhouse also seem to be less hairy and

thinner-textured than those seen in the field.

The flattened orbicular sporocarps of M. uncinata are the result of the sporan

gia's failing to develop fully. I initially took this to be evidence that the species

might be a hybrid, but finally concluded that abortion of sporangial development

might be environmentally induced. Sporocarps of greenhouse plants often do not

develop fully before rotting, with the result that they are flattened in appearance. Shattuck (1910) found that megaspore abortion could be induced by chilling the

sporocarps.

This failure of the sporangial contents to develop can alter the appearance of

the sporocarp considerably. For example, a flattened sporocarp with a transverse

perimeter of 12 mm would have a width of about 6 mm. If the sides of this

sporocarp were distended by the contents so that the sporocarp attained a circular

cross section, the width would be only 3.8 mm. The cross section of most sporo

carps is more nearly elliptical, so that a width between these two extremes, or 4.9

mm, would be more likely. This is a common sporocarp width for M. vestita

throughout its range. I therefore interpret Marsilea uncinata to represent populations of M. vestita

subsp. vestita that are exhibiting extremes of morphological variation, some of it

probably environmentally influenced, at the southeastern limit of its range. Al

though it is not yet clear what specific cues might be responsible for such modifi

cation, it is true that the zone in which "M. uncinata" grows is marked by higher rainfall and a longer growing season that the range of M. vestita to the north and

west.

Pubescence of the leaflets, used to separate M. mucronata of the Great Plains

from M. vestita subsp. vestita of the West Coast, does vary geographically. Plants

from Montana and California, grown alongside those from Texas in the green house, characteristically had the adaxial surfaces of the leaflets uniformly covered

with long appressed hairs, while the plants from Texas had short, irregularly distributed hairs on the adaxial surfaces of the leaflets. The extremes are strik

ingly different, but glabrous plants also occur occasionally in southern California

and northern Mexico, and I have not been able to find any other characters that

would distinguish M. vestita subsp. vestita from M. mucronata. I thus concur with

those recent floristicians (e.g., Mickel 1979; Petrik-Ott 1979) who combine the two species.

At the other extreme of variation are exceedingly small plants. In M. vestita




var. minima and M. fournieri the leaves are exceedingly small, but the sporocarps are of typical size and form for M. vestita subsp. vestita. In other specimens collected by Schaffner from near the type locality of M. fournieri, however, and in

specimens collected by M. E. Jones in Zacatecas, Mexico, the sporocarps are also

reduced in size. Such specimens resemble M. mollis but have appressed hairs,

sporocarps that are perpendicular to the peduncle, and a distinct superior tooth on the sporocarp. A similar reduction in sporocarp size was observed in M.

ancylopoda (no. 6). As for M. uncinata, a correlation between extreme morphol ogy and range limits under extreme ecological conditions can be noted, this time

high temperatures and very low rainfall.

10b. Marsilea vestita subsp. tenuifolia (Engelmann ex A. Braun) D. M. Johnson, comb. nov. Marsilea tenuifolia Engelmann ex A. Braun in Kunze, Amer.

J. Sei., ser. 2, 6: 89. 1848. Marsilea vestita var. tenuifolia (Engelmann ex

A. Braun) Underwood & Cook, Bull. Torrey Bot. Club 14: 92. 1887.

Zaluzianskia tenuifolia (Engelmann ex A. Braun) Kuntze, Revis, gen. pi. 2: 823. 1891.?Type: U.S.A. Texas: ponds along the Pierdenales [Peder

nales], 1846, Lindheimer IV 745 (holotype: MO!; isotypes: BM! G! GH! K! MO! NY! PH! S! UC! US!).

Leaflets of land leaves 1.1-1.7 cm long, 0.1-0.4 cm wide, linear to slightly falcate, asymmetrical, with sparse appressed hairs adaxially and abaxially, with concave to straight lateral margins and truncate to oblique, entire to remotely denticulate terminal margins; floating leaves not seen. Peduncles 0.8-5 mm long, 0.2-0.5 mm thick. Sporocarps 4.7-8.0 mm long, 3.5-5.5 mm wide, 1.5-2.0 mm

thick; raphe 0.8-2.0 mm long, superior tooth 0.2-0.6 mm long, acute. Habit, rhizome in water, mature sporangia and spores not observed. Figs. 5d, 17f, i.

Specimens Examined. U.S.A. Texas: Burnet Co., SW side of Granite Mtn, Correll & Johnston

17338 (GH, LL; st); 12 mi W of Burnet, Inks Lake State Park, Hartman 898 (KANU f ); Inks Lake, 11

Aug 1941, Tharp s.n. (CAS st, MO f, NY f, PH f, TAES f, TEX st, UC st, US f). Llano Co., creek

bed, 15 Aug 1940, Tharp s.n. (CAS, F, GH, LL, MO, NY, PH, UC, US; st except one at GH); creek

near Kingsland, Whitehouse 18480 (MICH, NY, UC, US; st). County unknown, Wright s.n. (G, GH,

NY, US; f).

Vegetatively subsp. tenuifolia differs from subsp. vestita by its exceedingly narrow leaflets, which are like those of M. nashii. Unlike M. nashii, however,

subsp. tenuifolia does not have sporocarp characters that separate it from subsp. vestita, which it resembles closely in size, shape, and angle of the sporocarp. In

addition, occasional specimens of subsp. vestita, such as Kiener 17144 from Fill more Co., Nebraska, and Tracy 8302 from Taylor Co., Texas, may have leaflets that are almost as narrow as those of subsp. tenuifolia. It might thus be considered

appropriate to regard this taxon simply as another morphological variant within M. vestita, were it not for its peculiar biogeography (Fig. 19). The granitic Llano

Uplift of central Texas, where M. vestita subsp. tenuifolia grows, is an area of

peculiar geology and soils that harbors other endemics, such as the amphibious Isoetes lithophila Pfeiffer. To point out its morphological and biogeographical peculiarities, and at the same time to suggest the closeness of this taxon to M. vestita subsp. vestita, I have recognized M. tenuifolia as a subspecies of M. vestita.




FIG. 19. Distribution of Marsilea macropoda, M. vestita subsp. vestita, M. vestita subsp. tenuifo lia, and M. macropoda x vestita in Texas.

11. Marsilea nashii Underwood in Britton, Bull. New York Bot. Gard. 4: 137. 1906.?Type: Bahamas. Inagua, Smith's Thatch Pond, 2 Nov 1904, Nosh

& Taylor 1411 (holotype: NY!; isotypes: F! US!).

Plants forming dense carpets. Rhizome 0.3-0.8 mm thick, brown to black, the

apices covered with fulvous hairs, bearing conspicuous short shoots at nodes,




nodal roots 0.1-0.3 mm thick, internodes 0.6-5.7 cm long; rhizome under water

0.3-0.7 mm thick, green or straw-colored, glabrous, internodes 3.1-5.0 cm long. Land leaves with terete to slightly canaliculate, pilose to glabrous petioles 3.1

10.7 cm long, 0.1-0.5 mm thick, leaflets 0.5-1.5 cm long, 0.1-1.0 cm wide, often more than 5 times as long as wide, linear, falcate, or cl?vate, virtually glabrous

adaxially and thinly hairy abaxially; floating leaves with terete flexuous petioles 25-31.5 cm long, 0.4-0.6 mm thick, leaflets 1.4-1.6 cm long, 1.2 cm wide, cun?ate, slightly asymmetrical; hydropoten irregularly distributed or absent. Fer

tile leaves produced on land, bearing solitary sporocarps at the base on erect or

slightly decumbent peduncles 2.8-14.0 mm long, 0.3 mm thick. Sporocarps 3.7

6.2 mm long, 3.6-4.2 mm wide, 2.5 mm thick, nearly round to elliptical in lateral

view, ovate to elliptical in cross section, slightly to strongly nodding, dark brown to black, covered with white hairs but soon glabrate; raphe 1.1-2.4 mm long, inferior tooth blunt, up to 0.7 mm long, superior tooth 0.3-0.7 mm long, straight and acute with a broad base; sporocarp veins ca 20, forking midway and anasto

mosing at the tips. Sori 15-20 per sporocarp, attached to a sorophore with a free

tip, 30 microsporangia and 2-15 megasporangia per sorus. Microspores 22-40 per

sporangium, 75-80 |xm in diameter; one-third to one-half of the spores in a

sporangium irregular, brownish, and with a maximum dimension of 35?55 |xm.

Megaspores 480-540 |xm long, 400-420 (xm wide, with an apical papilla 50-65 jxm

long. Figs. 4d, 5e, 6, 17d, e.

Phenology. If sufficient water is available, M. nashii probably persists all

year. Sporocarps have been seen on collections from all months except April,

August, and September. Distribution. (Fig. 16). In wet freshwater depressions and ponds over limestone,

near sea level, from Cuba, several nearby islands in the Bahama Archipelago, and

Barbuda in the Lesser Antilles. Reports of M. vestita from the Caribbean (Correll 1976; Proctor 1977) were based on broad-leafleted specimens of M. nashii.

Representative Specimens. Bahama Archipelago. Acklin's Island: Pawkey Bay, Brace 4425

(F, NY; st). Grand Turk: North Wells, Correll 46513 (F, FTG, LL; st); just W of North Wells, Correll 46631 (F, FTG, GH, LL, MO; f); Waterloo, Correll 49212 (FTG, NY; st); near W end of airfield, Proctor 8798 (PENN f). South Caicos Island: Wilson 7673 (F, K, MO, NY; st). Great

Inagua: Conch Shell Point Pond, Barrington 195 (VT f); Smith's Thatch Pond N of Lantern Head, Correll 47461 (BM, FTG, MO, NY; f ); Horse Pond, just N of Matthewtown, Correll 49945 (BM, F, FTG, NY; f ); Smith's Thatch Pond N of Lantern Head, Correll 49968 (FTG, NY; f ); pond 1 mi from ocean, Dunbar 157 (A f ).?Cuba. Cam ague y : Cayo Sabinal, Ekman 15488 (G, NY, US; f ). Isla de la

Juventud [Isle of Pines]: Boquer?n Ensenada de Siguanea, Britton et al. 14499 (NY, US; f ). Oriente:

Guant?namo region, vicinity of Uvero Beach, ca 2-3 mi W of mouth of Rio Yateras, Webster &

Wilbur 3963 (GH, MICH; f).?Barbuda: Horse Pond, Charter for Box 594A (BM f ); near Bull Hole, Box 594 (BM f ).

Marsilea nashii may usually be distinguished from other West Indian species of Marsilea by the narrow leaflets. Specimens with broader leaflets may be recog nized by the basal sporocarps borne above ground and the asymmetry of the

leaflets; in M. poly carpa the sporocarps are borne in a row on the petiole and the leaflets are symmetrical, and in M. ancylopoda, which also has fairly symmetrical leaflets, the sporocarps are produced under ground. Marsilea nashii is similar to

M. vestita, but has sharply nodding sporocarps rather than slightly nodding to

slightly ascending sporocarps.




12. Marsilea villosa Kaulfuss, Enum. filie. 272. 1824. Zaluzianskia villosa (Kaul

fuss) Kuntze, Revis, gen. pl. 2: 823. 1891.?Type: Hawaii. Owahu

[Oahu], Chamisso s.n. (LE ?).

Plants forming extensive colonies. Rhizome 0.3-0.7 mm thick, reddish brown to black, densely pinkish brown tomentose at apices, sparsely pilose to glabrate

proximally, with well-developed nodal short shoots, nodal roots 0.1-0.4 mm

thick, sparsely branched, internodes 0.4-3.5 cm long. Land leaves with terete to

canaliculate, pilose to glabrate petioles 2.8-24 cm long, 0.2-0.4 mm thick, leaflets 0.4-2.4 cm long, 0.2-2.1 cm wide, cun?ate or occasionally linear, glabrate above, villous to glabrate below, with straight or convex inner lateral margins and re

motely denticulate terminal margins; floating leaves not seen. Fertile leaves bear

ing solitary sporocarps at the base on erect to slightly oblique peduncles 1.9-6.0 mm long, 0.3-0.4 mm thick, the point of attachment of the peduncle to the

petiole often obscured by hairs. Sporocarps 4.3-5.0 mm long, 3.0-4.1 mm wide, 1.5-2.5 mm thick, oblong to rectangular in lateral view, ovate to elliptical in cross section, often obliquely truncate at the apex, perpendicular to the peduncle,

light to dark brown, densely tomentose to glabrate; raphe 1.4-1.9 mm long, inferior tooth 0.3-0.6 mm long, blunt, superior tooth 0.5-0.8 mm long, acute

with a broad, often thickened base; sporocarp veins 15-18, forking midway, anastomosing or free at tips. Sori 14-18 per sporocarp, attached to a sorophore

with a free blunt tip, 19-36 microsporangia and 3-10 megasporangia per sorus.

Microspores 42-64 per sporangium, 65-85 |xm in diameter; 2-4 spores per spo

rangium brown, misshapen, and 15-35 |xm long. Megaspores 555-625 |xm long, 440-475 |xm wide, plus an apical papilla 40-50 |xm long. Fig. 17a-c.

Phenology. Fertile collections are known from December, March-May, and

July. Distribution. Forming extensive turfs in seasonally wet depressions in clay or

calcareous sand from sea level to 100 m in the Hawaiian Islands. Although M. villosa has been collected from the islands of Oahu, Molokai, and Niihau, all recent collections have come from Koko Head, Oahu, and I do not know if the

species still exists elsewhere. It should be sought, however, on other Pacific

Islands; a sterile specimen from Tahiti (Barclay s.n., K) strongly resembles M. villosa in its hairy leaflets with straight margins.

Representative Specimens. Hawaii. Molokai: west of Mokio, Degener & Wiebke 3215 (G st, MICH f, st); Anapuka, West Molokai, Fosberg 29594 (MICH st). Niihau: Loe Lake, 2 mi N of

Puuwai, St. John 23600 (K f). Oahu: Koko Head, Carlquist 1692 (MICH f); Iheihelauakea Crater, Koko Head, above Hanauma Bay, Crosby & Anderson 1549 (MICH st); Lualualei Valley, 1 mi E of

Mauna Kuwale, Degener et al. 9049 (G, K, MICH, NY; f); Koko Head crater ?above Hanauma Bay,

Fosberg 9704 (MICH f); Koko Head, Fosberg 29662 (MICH f); Ewa, 13 Apr 1932, Lyon s.n. (COL, K, MICH; f); Koko Head, Webster 1480 (MICH f); Koko Head S of Beach Park, Wagner 84087 (MICH f). Island unknown, Gaudichaud 166.164 (G st).

The large toothed sporocarps and absence of internodal roots support the

relationship of this species to the North American marsileas, as proposed by Braun (1871). I disagree with Forbes (1920), however, who considered the west ern North American M. vestita conspecific with M. villosa. The former has leaflets




with concave inner lateral margins and globose to ovoid sporocarps, while the

latter has leaflets with straight or convex inner lateral margins and oblong or

rectangular sporocarps. The obliquely truncate tip of the sporocarp (Fig. 17c) and

the smooth black surface without conspicuous trichome scars of old sporocarps of

A?. villosa also occur in M. exarata A. Braun of Australia. It is of course possible that these differences could be the result of fixation of slightly atypical characters

in island populations of M. vestita, but similar plants are not known from the

mainland, and these characters seem to be consistent.

Putative Hybrid between Members of Marsilea Section Nodorhizae

9. Marsilea macropoda x 10. M. vestita. Figs. 5b, 19.

Specimens Examined. U.S.A. Texas: Blanco Co., Pedernales Falls State Park, Johnson 708

(MICH st); Reeves 6350 (ASU f). Brazos Co., Little Brazos River bridge of Hwy 21 W of Bryan,

Massey 591 (TEX f); overflow bottoms of Brazos River, Herrington, Palmer 13444 (MICH, US; f).

Kleberg Co., Kingsville, Jones 29011 (MO, TAES, UC; f); Riviera, Fisher 41150 (MO, US; f). County

unknown, 1835, Drummond s.n. (G, MO; f).

Specimens of this hybrid have the habit of M. macropoda, i.e., large size and

broad leaflets with long dense overlapping hairs, but with sporocarps that are

relatively short-peduncled (5-17 mm) and which bear a prominent superior tooth.

The putative parents of this hybrid are sympatric over much of south-central

Texas (Fig. 19), and and the hybrid may be more common than is recognized here; many sterile collections of Marsilea from Texas that might represent this

hybrid cannot be positively identified.

Little is known about the ecology of M. macropoda x vestita. One collection

is from clay soils of a river bottom, and I found it growing in wet calacareous sand

along the Blanco River; neither parent was growing with it.

Doubtful and Rejected Species

Marsilea capensis A. Braun, Monatsber. K?nigl. Preuss. Akad. Wiss. Berlin

1863: 428. 1864.

A mixed collection of Marsilea from Buenos Aires Province, Argentina, at SI

(Cap. Federal, Paternal FCCBA, Burkart3345), includes a small specimen of this

African species among the more robust specimens of M. ancylopoda. If this

specimen was not included on the sheet through a mounting or labeling error, it

represents the first record of M. capensis from the Western Hemisphere. In order

to alert South American collectors to its possible presence, I provide the following brief description.

Marsilea capensis would be assigned to sect. Marsilea, as it has internodal

roots and a prominent raphe and superior tooth on the sporocarp. The leaves are

nearly glabrous, with petioles 4-5 cm long and thin, oblanceolate leaflets that are

often emarginate or bilobed at the apices. The sporocarps are borne on un

branched peduncles 6-8 mm long, which are attached 2-2.5 mm above the petiole base; the sporocarps are 3.5-4 mm long, somewhat flattened, rounded or

obliquely truncate at the apex, and covered with appressed hairs.




Marsilea longipes Austin, Bull. Torrey Bot. Club 3: 23. 1872.?Type: U.S.A.

Oregon, 1871, Hall s.n. (GH). Austin described M. longipes as being relatively glabrous, with a sporocarp

peduncle one inch long. The Oregon specimens of Marsilea I have examined are

relatively hairy, and have a maximum peduncle length of Y* inch. The description fits specimens collected by Hall near Dallas, Texas, but I found no annotations

that might have confirmed such an error in citing the locality. In 1872 a corre

spondent of the Bulletin of the Torrey Botanical Club questioned the accuracy of

Austin's description, but no explanation was given by Austin. I found no speci men from the Gray Herbarium collected by Hall in Oregon that even remotely

approached Austin's description, and the name is here set aside as one of un

known application.

ACKNOWLEDGMENTS

This paper is based on a doctoral dissertation submitted to the Horace H. Rackham School of

Graduate Studies, University of Michigan. I thank W. H. Wagner, Jr., W. R. Anderson, C. B. Beck,

G. M. Hatfield, E. G. Voss, J. M. Beitel, D. Barrington, M. G. Price, M. Bruegmann, B. Le?n, W.

C. Taylor, and S. Taylor for their help in various ways and suggestions during the course of this

project. I also thank the curators of the following herbaria, who made specimens available to me for

study (abbreviations are from Holmgren et al. 1981, except for CORO, which is the herbarium of the

Proyecto Flora Falc?n, Coro, Venezuela, and VZM, which is the herbarium of the Jardin Bot?nico,

Maracaibo, Venezuela): ASU, B, BA, BM, C, CAS, CHAPA, COL, CM, CORO, CR, CTES, DS,

DUR, ENCB, F, FTG, G, GH, JEPS, K, KANU, KLU, LL, LP, M, MARY, MEXU, MICH, MO,

MSC, MY, NLU, NO, NY, OKL, OKLA, P, PENN, PH, PORT, R, RB, RM, S, SI, SMS, TAES,

TEX, TRIN, U, UC, US, USM, VEN, VT, VZM, WS, and Z. For assistance and advice in the field I

thank E. L. Schneider, D. Huffman, A. Krapovickas, C. A. Crist?bal, A. Schinini, R. Vanni, T. M.

Pedersen, N. Tur, O. Boelcke, J. A. Steyermark, O. Huber, V. Medina, R. Wingfield, Y. Baksh, R.

Ramkissoon, L. D. G?mez, and S. D. Koch. The help of C. A. Jermy, C. D. Adams, A. Paul, B. S.

Parris, and P. Edwards during my visit to English herbaria is appreciated. For caring for live plants used in this study, I thank the staff of the University of Michigan Matthaei Botanical Gardens,

especially M. Hommel and M. W. Chase. P. M. Richardson allowed me to work in his phytochemical

laboratory, for which I am appreciative. For comments on this manuscript, I thank J. T. Mickel, A. R.

Smith, C. Anderson, and an anonymous reviewer. Finally, I thank N. A. Murray for assistance and

advice in the field, and in preparation and revision of the manuscript. Financial support for this project was provided by the Horace H. Rackham School of Graduate

Studies and Department of Botany, University of Michigan, Sigma Xi, and National Science Founda

tion Doctoral Dissertation Improvement Grant DEB-8118247.

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APPENDIX

The herbarium specimens listed here are the source of sporocarps that yielded sporophytes upon

germination. The number in parentheses is the age in years of the collection at the time of germination.

Sporophytes obtained from contents of a single sporocarp: M. ancylopoda: Coronado 235 (GH), Peru (28); Herter 844c (US), Uruguay (48); Johnson 777

(MICH), Venezuela (3). M. macropoda: Correll 32314 (GH), Texas (18); Cory 36057 (TAES), Texas (44). M. minuta: Davison TR-12 (MO), Trinidad (6). M. mollis: Garc?a P. 987 (F), Mexico (4); Johnson 759 (MICH), Argentina (2). M. polycarpa: Wagner 82020 (MICH), Puerto Rico (1). M. vestita: Brandegee s.n. (F), California (77); Raven 2269 (CAS), California (35).

Additional collections yielding sporophytes (number of sporocarps not recorded, or more than one). M. anyclopoda: Johnson 758 (MICH), Argentina (0.3). M. crenata: Campbell s.n. (MICH), Philippines (68). M. deflexa: Johnson 794 (MICH), Venezuela (3.5). M. ephippiocarpa: Chase 2255 (NY), Zimbabwe (35). M. gibba: Faden 6911293 (NY), Kenya (14). M. mollis: Murray & Johnson 1404 (MICH), Mexico (0.5); Pringle s.n. (F), Mexico (90). M. nashii: Barrington 195 (VT), Bahamas (13); Correll 49945 (F), Bahamas (6.5). M. oligospora: Suksdorf s.n.[716] (GH), Washington (101/102). M. polycarpa: Allen & Alston 1867 (US), Panama (46). M. quadrifolia: Johnson 682 (MICH), Kentucky (0.5). M. vestita: Blanchard s.n. (MICH), Montana (35); Soxman 106-a (US), Texas (46). M. villosa: Wagner 84087 (MICH), Hawaii (1).

NUMERICAL LIST OF TAXA

1. M. quadrifolia 2. M. minuta

3. M. deflexa

4. M. polycarpa 5. M. crotophora 3. x 4. M. deflexa x polycarpa 3. x 5. M. xsubangulata (M. deflexa x cro

tophora) 6. M. ancylopoda

7. M. oligospora 8. M. mollis

9. M. macropoda 10a. M. vestita subsp. vestita

10b. M. vestita subsp. tenuifolia

11. M. nashii

12. M. villosa

9. x 10. M. macropoda x vestita

INDEX TO NUMBERED COLLECTIONS EXAMINED

The number in parentheses refer to the taxon in the Numerical List of Species above, and are the

same as those assigned in the text.

Abrams, L. 3852 (10a); 5392 (10a); 6324 (10a). Acosta A., C. E. 785 (6).

Ahart, L. 3059 (10a); 4404 (10a). Albers, C. C. 46094 (9). Allen & Alston 1867 (4). Alston, A. H. G. 5639 (6); 5874 (6); 6354 (6);

7698 (6); 8831 (4); 8840 (6). Anderson, L. C. 1299 (7).

Andr?, E. 1899 (6); 1901 (6). Arbo et al. 1667 (6).

Arechavaleta, J. 461 (6).

Aristeguieta, L. 4151 (4); 6463 (3). Aristeguieta & Ferrer 12546 (4). Amoldo 408 (6); 497 (6). Arregu?n, M. L. 589 (8); 596 (8). Ars?ne, G. 18763 (10a).

Asplund, E. 15265 (6). Bacigalupi, R. 4289 (10a); 6369 (10a); 8719

(10a). Bacigalupi et al. 2498 (10a).




Baker, C. F. 2281 (5); 4228 (4). Baker, W. H. 5653 (10a).

Balansa, B. 1127 (6); 1884 or 1885 (6). Ball, C. R. 492 (10a).

Barker, W. T. 1809 (10a); 1836 (10a). Barkley, F. A. 1190 (10a); 1220 (10a); 2554

(10a); 13130 (10a); 13396 (10a); 14344 (9). Barkley & Johnson 6112 (10a). Barkley & Proctor 38651 (6). Barrington, D. S. 195 (11). Bernoulli & Cario 144 (4); 145 (3). Bethel et al. 3994 (10a). Black et al. 52-14264 (4); 54-16605 (4). Blake, S. F. 7184 (1). Blanchet 2368 (4); 2409 (4). Bond et al. 131 (4).

Box, H. E. 594 (11).

Brace, L. J. K. 4425 (11).

Bradshaw, K. 348 (10a); 379 (10a). Bravo, H., H. 523(3).

Breedlove, D. 8316 (8); 37135 (8). Brenes, A. M. 22653 (4).

Brigada Vegetaci?n Acu?tica 239 (8).

Bristow, J. M. 1 (4). Britton & Britton 7340 (6); 9718 (4). Britton & Cowell 1486 (4). Britton & Hollick 2146 (4). Britton et al. 6726 (4); 6776 (4); 8872 (6); 14499

(11). Brooks, R. 435 (10a); 460 (10a); 465 (10a); 1516

(10a); 13292 (10a). Brown, W. V. 2242 (1).

Burkart, A. 449 (6); 3345 (6 + M. capensis); 8020 (6); 20188 (6); 24702 (6); 26671 (6).

Burkart & Troncoso 26116 (6); 27161 (6). Burkart et al. 30219 (6); 30220 (6). Burkhalter, J. R. 5672 (9).

Burr, R. D. 174 (10a).

Bush, B. F. 173 (10a); 838 (10a). Cabrera, A. 7250 (6). Cabrera et al. 26139 (6). Calder & Savile 8175 (10a); 10140 (10a). Cameron, C. E. R. 48 (9).

Canby, W. 400 (7).

Carlquist, S. 1692 (12). Carranza & Arias 44 (4).

Carter, A. 5934 (10a). Carter & Kellogg 3227 (10a); 3228 (10a). Carter & Moran 5394 (10a). Castellanos 17496 (6).

Charter, C. F., for H. E. Box 594a (11).

Chase, V. H. 7607 (9).

Christ, J. H. 8528 (10a); 12915 (7); 19130 (7). Churchill, S. P. 2300 (10a); 6585 (10a). Clover, E. U. 18 (9); 115 (9). Combs, R. 690 (4).

Coronado, P. S. 235 (6).

Correll, D. S. 19756 (9); 26835 (9); 32294 (9); 32314 (9); 32766 (10a); 46513 (11); 46631

(11); 47461 (11); 49212 (11); 49945 (11); 49968 (11).

Correll & Correll 29940 (10a); 33044 (10a); 36062

(10a); 38274 (9); 39452 (8); 40036 (10a). Correll & I. M. Johnston 17315 (10a); 17338

(10b); 17525 (9); 17623 (10a); 17877 (10a); 17918 (9); 18017 (9).

Correll & M. C. Johnston 25500 (10a). Correll & Ogden 25302 (10a); 25344 (9); 25356

(10a); 28347 (10a); 28362 (10a). Correll & Wasshausen 27784 (10a). Correll et al. 28069 (10a); 28204 (9). Cory, V. L. 5636 (9); 8821 (10a); 8903 (10a);

18108 (9); 18110 (9); 19180 (9); 19181 (9); 28439 (9); 32713 (10a); 34462 (10a); 36057

(9); 36325 (9); 36326 (9); 38356 (10a); 45355 (9); 49356 (9); 51449 (9).

Cota, F. M. 23 (10a).

Cotton, J. S. 1347 (10a). Coville & Funston 1275 (10a). Croft, M. B. 121 (9).

Crosby & Anderson 1549 (12). Crutchfield, J. R. 2 (10a); 168 (10a); 734 (10a);

1157 (10a); 1257 (9); 1424 (8); 1580 (10a); 1787 (10a); 2902 (9); 2949 (10a); 2996 (9); 3536 (10a); 3627 (10a).

Curtiss, A. H. 220 (4).

Cusick, W. C. 1007 (7).

Daguerre 230 (6).

Davidse, G. 3831 (3 x 4). Davidse & Gonz?lez 14783 (3). Davidson et al. 1821 (1).

Davis, D. M. 288 [R15] (4). Davison, S. E. TR-12 (2).

Davy, J. B. 3308 (10a).

Dawson, G. 327 (6).

Degener & Wiebke 3215 (12). Degener et al. 9049 (12).

Delascio, F. 6779 (4). Delascio & L?pez 8836 (4). Demaree, D. 18969 (10a); 19265A (10a); 19442

(10a); 21061 (10a). Dorn, R. D. 3176 (10a). Drummond II 39 (9 x 10). Dunbar, H. F. 94 (11); 157 (11); 235 (11). Dwyer, J. 2111 (1).

Eastwood, A. 11193 (10a). Eastwood & Howell 5103 (10a). Edwards, M. T. 789 (9).

Ekman, E. L. 212 (4); 3340 (4); 4803 (4); 10033

(6); 10583 (4); 12122 (4); 15488 (11). Elias 1370 (4); 1374 (4). Elizondo & Sanchez FaI-3190 (8).

Ertter, B. 3894 (7); 3958 (10a). Eyerdam et al. 23283 (6).




Farley, S. 78-41 (7).

Fasse?, N. C. 13562 (1); 28419 (8). Feddema, C. 2532 (4). Ferris & Duncan 3099 (9). Fessenden, G. R. 5592 (1).

Fisher, G. L. 3798 (9); 41150 (9 x 10). Fleetwood, R.T. 2030 (10a); 3286 (9). Flowers, S. 3247 (10a).

Fosberg, F. R. 9704 (12); 29594 (12); 29662

(12); 44302 (1). Freeman, W. F. 7946 (2).

Fr?es, R. 1858 (4); 24-865 (5). Garcia, P., J. 987(8).

Gardner, C. 2760 (3).

Garre?, A. O. 5375 (7).

Gaudichaud, C. 166.164 (12).

Gephardt, H. B. 426 (10a).

Geyer, C. A. 71 (10a); 450 (10a). Gibert 1319 (6); 1320 (6). Gier, L. J. 8446 (1).

Gierisch, R. K. 718 (7). Gierisch & Esplin 3597 (7). Gill & Gill 217 (9). Gillis, W. T. 11738A (11); 14500 (11); 14970

(4). Glaziou, A. 5213 (2); 10218 (4); 16648 (3). Gleason, J. 559 (10a). Gonz?lez Medrano, F. 216 (9).

Goodding, L. 43-14 (10a); 166-41 (10a); 190 45 (10a).

Goodman, G. J. 6242 (10a); 6674 (10a). Goodman & Lawson 8422 (10a).

Gorman, M. W. 843 (10a); 3654 (10a); 5924

(10a). Gould, F. W. 6405 (9). Gould & Hycka 8147 (9). Greenfield & Lehto 110 (10a). Griffith, F. 3465 (10a). Griffiths, D. 4734 (10a). Groth, B. H. A. 154 (10a).

Hall, C. C. 185 (10a).

Hall, D. W. 414 (10a).

Hall, E. 697 (10a); 860 (10a); 861 (10a). Hall & Harbour 254 (10a). Hall, G. W. 2372 (10a); 2738 (10a). Hall, H. M. 9840 (10a); 11217 (10a). Harger, E. B. 6817 (1).

Harms, L. J. 1137 (10a).

Harriman, N. A. 11408 (9).

Harris, S. A. TP 380 (4).

Harris, W. 6707 (4); 8510 (4); 11827 (4); 12720 (4).

Harrison & Garrett 10505 (7).

Hartman, C. V. 604 (8); 893 (10a). Hartman, E. 898 (10b). Haskell & Darrow 2170 (10a). Hasse, H. E. 2 (10a).

Hatschbach & Scherer 30470 (5). Hauser, L. 2197 (10a).

Haynes, R. R. 5440 (9).

Hayward, H. E. 559 (10a); 2576 (10a). Heller, A. A. 11633 (10a).

Hellquist, C. B. 10934 (1).

Henderson, L. F. 530 (10a); 2431 (10a). Herter 844 (6); 844c (6); 84810 (6). Hicken, C. 506 (6).

Higgins, L. C. 7672 (10a).

Hill, S. R. 4705 (10a); 5520 (9); 10504 (10a); 10535 (10a).

Hill 241 (8). Hindshaw, H. H. 35 (10a). Hitchcock & Muhlick 8359 (10a); 13728 (10a). Hoehne, F. C. 5783 (5).

Holland, W. W. 1993 (10a).

Holmgren, A. H. 1696 (10a).

Holmgren & Holmgren 7297 (10a). Holm-Nielsen et al. 7220 (6).

Hoover, R. F. 1125 (10a).

Horr, W. H. 3693 (10a). Howard & Howard 9521 (4). Howell, J. T. 2003 (10a); 2009 (10a); 2159

(10a); 4777 (10a); 12194 (10a); 13215 (7); 36949 (10a); 37856 (10a); 38683 (10a); 46142 (7); 47460 (10a); 52202 (10a).

Howell & True 48154 (10a). Howell, T. J. 483 (10a).

Hume, E. P. 194 (12).

Humfeld, P. H. 445 (10a); 871 (10a); 900 (10a). Irwin et al. 31630 (6). Jameson 394 (6).

Jepson, W. L. 18035 (10a).

Jermy, A. C. 10821 (4). Jim?nez M., A. 348 (3).

Johnson, D. M. 643 (10a); 682 (1); 687 (10a); 691 (9); 698 (10a); 702 (10a); 708 (9 x 10); 714 (9); 718 (9); 727 (10a); 729 (10a); 733

(10a); 758 (6); 759 (8); 760 (8); 769 (6); 776 (6); 777 (6); 778 (3); 779 (6); 780 (6); 781 (6); 783 (6); 784 (4); 785 (4); 790 (4); 792 (3 x 4); 793 (4); 794 (3); 797 (2); 798 (2); 799 (2); 800 (2).

Johnston, E. L. 99 (10a); 1039 (10a); 1116

(10a). Johnston, I. M. 1979 (10a).

Johnston, J. R. 1311 (4). Johnston et al. 11448 (10a). Jones & Jones 46493 (1). Jones, M. E. 157 (10a); 23510 (6); 26034 (10a);

29011 (9 x 10). Kearney, T. H. 1 (10a); 82 (10a).

Kellerman, W. A. 7721 (6).

Kiefer, L. L. 498 (10a); 531 (10a). Kiener, W. 17144 (10a); 19386 (10a). Koch, S. D. 74196 (8); 74218 (8).




Kolstad & Harms 1581 (10a). Koyama & Agostini 7215 (4). Kral, R. 28908 (10a); 47120 (9). Kramer & Hekking 2742 (4). Krapovickas & Schinini 35030 (5). Kuhlmann 916 (4). Lachica & S?nchez FaI-2118 (3). Lake & Hull 657 (10a). Landry, G. P. 7895 (9).

Lane, F. C. 222 (1).

Lasser, T. 127 (3).

Lawrence, W. E. 2154 (7). Lawson et al. 399 (10a); 451 (10a).

Leiberg, J. B. 726 (10a). Lehmann 8714 (3). Lehto, E. 12872a (10a); L20254 (8). Lemmon, J. G. 227 (7); 2896 (8). Le?n & Ekman 4284 (4). LeSueur, H. 3 (9).

Letterman, G. W. 112 (10a); 635 (10a).

Levy, P. 268 (5).

Lewton, F. L. 13 (9); 175 (9); 837 (10a). Liebmann 2189 (4). Liesner & Gonz?lez 12125 (6). Lindheimer, F. Ill 573 [=394] (9); IV 745

[=374] (10b); IV 746 [=404] (10a); 1282

[=125] (10a); 1283 [=590] (10a). Little, E. L. 9253 (3 x 5); 9254 (3 x 5). Lorentz & Hieronymus 522 (6).

Lot, A. 1295 (5). L?tzelburg 21187 (3); 21231 (4); 21239 (4). Lundell, C. L. 2579 (3); 10668 (9); 11633 (10a). Lundell & Lundell 9083 (10a). Lusher & Goodding 143-45 (10a). Macbride & Payson 3844 (7). McCart et al. 42 (9).

McDougal, D. L. 901 (7).

McFarland, F. T. 46 (1).

McGregor, R. L. 2230; 3256; 3278; 3286; 3503; 3504; 3924; 3937; 3943; 3945; 3951; 3962; 3972; 3991; 4001; 4010; 4024; 4043; 4045; 4047; 4951; 7313; 10701; 13744; 17015; 18733 (all 10a).

Mackensen, B. 130 (9).

Macoun, J. 3052 (10a); 14208 (10a); 14208a

(10a); 14209 (10a); 14210 (10a). McVaugh, R. 16917 (8); 16968 (8); 17068 (8);

19287 (3); 24377 (8); 26535 (8); 26579 (8). Magrath, L. K. 6114 (10a).

Magrath & Weedon 5760 (10a). Maguire, B. 3173 (10a); 13154 (7); 21597 (7). Marie-Victorin & Alain 342 (4). Martinez Crovetto 10179 (6).

Mason, H. L. 4443 (10a). Mason & Smith 8346 (10a). Massey, J. R. 591 (9 x 10); 825 (10a). Mastrogiuseppe, J. 3006 (10a).

Maysilles, J. H. 7869 (8).

Metz, M. C. 691 (10a); 2133 (10a). Michener & Bioletti 14 (10a).

Mickel, J. T. 9673 (2).

Miller, B. 647 (1). Molina R., A. 13266 (3); 30448 (4). Montz, G. N. 5190 (10a).

Moore, J. W. 116 (4). Moore & Huff 18701 (10a). Moore & Moore 10550 (10a). Moore & Tryon 17578 (10a). Moore et al. 2274 (1).

Mora, L. E. 1415 (4).

Moran, R. 9191 (10a); 26036 (10a); 28429 (10a). Morel, I. 1570 (6); 1587 (6). M?nch, G. 83 (8). Muenscher & Winne 16506 (9). Munz, P. A. 10800 (10a); 12699 (10a). Munz & Johnston 5154 (10a).

Murray & Johnson 863 (3); 865 (3); 868 (3); 874

(6); 1401 (8); 1403 (8); 1404 (8); 1428 (8); 1458 (6); 1467 (1); 1583 (1).

Nash, G. V. 831 (6). Nash & Taylor 1411 (11). Neese, E. 12385 (7). Nelson & Macbride 1158 (7). Nelson & Nelson 6560 (7). Nelson, J. C. 474 (10a); 1983 (10a); 2946 (10a);

4188 (10a). Nielsen, E. L. 3570 (10a); 3607 (10a). Niles 698 & Reese 87 (8). Nobs & Smith 33 (10a); 1354 (10a); 1856 (10a). Orcutt, C. R. 5791 (9).

Ortega, 0.,R. 0-583(3).

Ortega & Griman 1913 (4). Osten & Rojas 8689 (3). Osterhout, G. E. 4142 (10a).

Over, W. H. 15876 (10a); 15877 (10a); 17437 (10a). Ownbey, M. 1334 (10a).

Palmer, Ed. J. 1878: 1010 (10a); 1892: 2766

(10a); 1896: 13 (8); 1898: 467 (10a). Palmer, Er. J. 10803 (9); 11245 (9); 11299 (9);

12148 (10a); 13350 (9); 13444 (9 x 10); 12465 or 13465 (10a); 30975 (8); 33587 (9); 33856 (9); 46540 (1); 53949 (1); 54495 (1).

Parish, S. B. 4527 (10a).

Parks, H. B. Rxl434 (9). Parks & Cory 8820 (10a); 15304 (10a); 15396

(10a); 16678 (10a); 17125 (9); 18109 (9); 19179 (9); 20618 (9); 31743 (10a); 31744

(10a); 32683 (10a). Pastore, F. 100 (6); 416 (6). Payson & Payson 2920 (7); 4437 (7). Peck, M. E. 16069a (7).

Pedersen, T. M. 1109 (6); 3980 (6); 4068 (3); 9823 (6).

Peirson, F. W. 10674 (10a).




Penneil, F. W. 10320a (9).

Petrik, A. J. 186 (10a).

Phillips, E. A. 805 (8). Pias, P. 4088 (10a).

Pickel, D. B. 3116 (2). Pinkava et al. 18239 (8).

Piper, C. V. 1736 (10a).

Pittier, H. 4555 (4); 10153 (3); 10697 (6). Porter & Porter 9399 (7). Prance et al. 26143 (5).

Pringle, C. G. 1975 (9); 2007 (8); 2434 (8); 2632

(8); 2729 (10a); 3122 (8). Proctor, G. R. 6182 (4); 8798 (11); 11534 (6);

27609 (6); 29976 (6). Proctor & Mullings 21961 (4). Pultz, L. M. 1814 (8). Pultz & Phillips 2573 (10a). Purer, E. A. 7302 (10a).

Purpus, C. A. 4525 (10a).

Quibell, C. H. 1825 (10a).

Ramcharan, E. K. 440 (2). Ramia & Montes 5510 (4). Raven, P. H. 2269 (10a); 8099 (10a); 9640

(10a); 10347 (10a); 16601 (10a); 16748

(10a). Reed, C. F. 52412 (1). Reeder et al. 3493 (10a).

Reese, W. D. 3347 (9).

Reeves, T. R5789 (8); 6149 (8); 6350 (9 x 10); 7266 (8).

Reveal, J. L. 2820 (10a); 2822 (10a). Reverchon, J. 1630 (9); 2465 (10a); 4325 (10a). Rich & Lewis 147 (10a). Richards, E. L. 3571 (10a).

Richardson, J. 338 (10a). Richardson & Robertson 856 (10a). Ripley & Barneby 5597 (10a). Ries & Sabinske 115 (10a). Robbins, G. T. 3957 (10a).

Roberts, M. L. 907 (1).

Rodriguez, J. V. 1583 (6).

Rogers, C. M. 6635 (9).

Rojas, T. 1834 (3); 8828 (5); 12885 (6). Rolleri, C. 9 (5). Rollins & Tryon 58319 (8). Roos, J. C. 5704 (10a).

Rose, F. H. 758 (10a).

Rose, J. N. 24194 (9).

Rosengurtt, B1434 (6).

Rossbach, G. B. 4798 (10a).

Roth, J. 616 (10a).

Rowell, C. M. 9083 (9); 10968 (10a). Rubtzoff, P. 5265 (10a); 5579 (10a). Rudd, V. E. 367 (3).

Runyon, E. 112 (10a).

Runyon, R. 263; 3464; 3465; 4390; 5270; 5271; 5272 (all 9).

Ruth, A. 603 (10a).

Ruthsatz, B. 260[5] (8). Rydberg, P. A. 6604 (10a).

Rzedowski, J. 2190 (8); 7319a (10a). Rzedowski & McVaugh 882 (8); 1331 (3). St. Hilaire 2652 (6). St. John, H. 4371 (10a); 6790 (7); 8060 (10a);

17414 (4); 23600 (12). St. John et al. 9687 (10a).

Sandberg, J. H. 901 (7).

Saunders, G. B. 231 (5). Scala 70 (6). Schaffner, J. G. 6 (8); 15 (10a); 90 (8). Schiede 836 (4). Schiller, I. 1047 (9).

Schinini, A. 22732 (6). Schinini & Bordas 14834 (6). Schinini et al. 16727 (6).

Schott, A. 1929 (9).

Schulz, E. D. 586 (10a); 2433 (10a). Schulz, J. P. 9958 (4).

Schuyler, A. E. 4501 (1). Scouler 338 (10a). Seiler, G. 5911 (10a).

Seigler et al. 1292 (10a); 1545 (10a). Seymour, F. C. 2576 (6); 20230 (1). Shafer, J. A. 11661 (4).

Sharsmith, C. W. 4047 (10a).

Shreve, F. 6998 (10a); 7116 (10a); 7165 (10a). Sintenis, P. 3805 (6); 6790 (4); 6852 (4). Small & Wherry 11893 (9). Smith, H. W. 218 (10a).

Sooter, I. 15 (10a).

Soxman, G. M. 57 (10a); 106-a (10a); 106-b

(10a); 218 (9); 262 (10a). Spegazzini, C. 17791 (6); 17794 (6); 17795 (6). Spruce, R. 42 (4); 417 (4); 6550 (6). Stahel, G. 41 (4).

Standley, P. C. 16616 (6); 26499 (4); 30765 (4); 40706 (10a); 56292 (6), 65703 (6).

Stanford, E. E. 439 (10a); 1181 (10a). Stanford & Blassingame 1223 (10a); 1236 (9). Stebbins, G. L. 4013 (7).

Stephens, S. 6583; 23846; 24286; 25181; 27125; 29475; 33268; 34743; 34762; 48801; 49273; 50100; 50673; 54289; 57622; 61158; 61406; 62504; 62516; 62870; 62956; 64503; 65532; 71042; 71200; 71477; 71609; 71663; 71856; 71917; 72242; 74954; 75384;71917; 72242; 74954; 75384; 76317; 76783; 76963; 79447; 80149; 80424; 80508; 81626; 82584; 84183; 84216; 84614; 84867; 86658; 87444 (ail 10a).

Stephens & Brooks, 357 (10a).

Stergios, B. 2491 (3). Stern et al. 17 (9).

Stevens, G. W. 383 (10a); 562 (10a).

Stevens, O. A. 1088 (10a); 1223 (10a).




Stevenson & Stevenson 1677 (4).

Steward, A. N. 7250 (10a).

Steyermark, J. A. 30117 (3); 94512 (6). Steyermark et al. 114577 (4).

Stinchfield, R. 360 (10a). Stoffers, A. L. 654 (6).

Storer, R. W. 390 (10a).

Stuckert, T. 15811 (6); 16414 (6). Suksdorf, W. N. 119 (10a); 227 (7); 2619 (7);

2620 (10a); 5412 (7); 8456 (10a). Svenson, H. K. 11152 (6).

Tavares, S. 626 (2); 841 (2). Tharp, B. C. 4269 (10a); 4270 (10a); 4271 (10a);

5556 (9); 8798 (10a); 43-510 (10a) 44285

(10a); 44286 (10a); 53-811 (10a). Tharp & Barkley 13875 (9). Tharp & Miller 51-425 (10a). Tharp & York 50-317 (10a). Tharp et al. 51-1535 (10a); 51-1603 (9); 3605

(9). Thomas, R. D. 29583 (10a); 58781 (10a). Thompson, J. W. 3790 (10a); 3846 (10a); 4882

(7); 9166 (7); 11676 (7); 11881 (10a). Thome, K. 2201 (7).

Tiehm, A. 3966 (10a). Tidwell, C. 72 (9). Tille?, S. S. 185 (7). Tolstead, W. L. 6924; 6947; 7221; 41569; 41570;

41576 (all 10a). Topping, D. L. 3518 (12). Toren & Trowbridge 5313 (7). Tracy, S. M. 8302 (10a); 9137 (10a); 9142a (9);

9416 (9). Traverse, A. 1061 (9).

Triana, J. 691 (3).

True, R. H. 413 (1).

Tur, N. 696 (6).

Tweedy, F. 632 (10a).

Twisselmann, E. C. 1646 (10a); 4777 (10a). Ugent, D. 1350 (9). Ule, E. 6866 (3); 7238 (6). Underwood, L. M. 337 (6); 1866 (4); 1878 (4);

2305 (6); 2911 (1). Urbatsch, L. E. 1197 (10a).

Velasquez, J. 760 (3); 842 (3). Visher, S. S. 19 (10a); 599 (10a); 2142 (10a). Voss, E. G. 10719 (1).

Wagenknecht, B. L. 4409 (10a); 4567 (10a). Wagner, W. H. 82020 (4); 82111 (8); 84087 (12). Waldorf ?tal. 13426 (10a).

Waller, F. R. 1258 (10a).

Ward, D. B. 7755 (9).

Waterfall, U. T. 5591 (10a); 6621 (10a); 7122

(10a); 8359 (10a); 10820 (10a); 13182 (9). Watson, S. 470, Montana (7); 470, Washington

(10a); 1372 (10a). Weaver, J. N. 646 (9). Webber & Kaiser 4787[5] (1). Weber, W. A. 13368 (10a).

Webster, G. 1480 (12). Webster & Wilbur 3052 (9); 3963 (11). Werff, H. van der 3518 (6).

Werner, D. 842 (8).

Wheeler, L. C. 1235 (10a); 3323 (10a); 3897

(10a); 3975 (7); 3993 (7). White, S. S. 1354 (9).

Whited, K. 1426 (10a). Whitehead, J. 799 (10a).

Whitehouse, E. 594 (9); 18480 (10b). Wiegand, K. M. 33 (10a).

Wiggins, I. L. 2119; 2637; 2796; 5422; 6101; 7848; 15162; 15491; 15506; 19151 (all 10a).

Wiggins & Ernst 636 (10a). Wiggins & Rollins 181 (10a). Wiggins & Wiggins 18197 (10a). Wilkinson, E. H. 35 (10a). Williams et al. 22416 (6). Williams & Williams 24536 (3). Williams, M. J. 79-136-3 (7).

Williams, W. I. 37842 (10a).

Wilson, P. 1103 (4); 1104 (4); 7673 (11). Windham, M. D. 0114D (8).

Wingfield, R. 6778 (6); 7042 (6); 8147 (6). Wolcott & Barkley 16T307 (6). Wolf, C. B. 3749 (10a).

Wolf, J. 174 (10a).

Wolff, S. E. 2252 (10a).

Woodland, D. W. 333 (10a).

Woolfolk, E. J. 79 (10a).

Wright, C. 811 (10a); 812 (9); 1799 (4); 1800 (4); 2111 (9); 2112 (10a).

York & York 54581 (10a). Young, K. 128 (10a).

Yuncker, T. G. 3615 (12).

INDEX TO SCIENTIFIC NAMES

Accepted names are in roman type; the main entry for each is in boldface. Synomyms are in

italics.

Acrostichum Linnaeus 30

Actinostachys

pennula Hooker 29

Adiantum Linnaeus 30

Aix

sponsa (Linnaeus) 24




Ammannia 62

Anas

acuta Linnaeus 24

clypeata Linnaeus 24

gibberfrons M?ller 24

platyrhynchos Linnaeus 24

rhynchotis Latham 24

superciliosa Gmelin 24

Anemia Swartz 29, 30

subg. Anemiorrhiza (Smith) Prantl 29

phyllitidis (Linnaeus) Swartz 30

Aponogeton 6

Arachis 18

Arcellites Miner 31, 32

Armoracia

aquatica 12

Artemisia 63

Aythya marila (Linnaeus) 24

Azolla Lamarck 30, 45

Balmeisporites Cookson & Dettmann 31, 32

Biziura

lobata (Shaw) 24 Butomus 6

Caperonia 41

Cardiomanes

reniforme Presl 30

Cassia 24

Celtis 24

Ceratopteris A. T. Brongniart 6, 30

Charadrius

vociferus Linnaeus 24

Chrysothamnus 63

Corystospermaceae 31

Curculionidae 27

Dalea 63

Davallia Smith 30

Dendrocygna arcuata (Horsfield) 24

eytoni (Eyton) 24 Dennstaedtia Bernhardi 30

Dennstaedtiopsis

aerenchymata Arnold & Daugherty 6

Desmodium 24

Echinodorus 49

berteroi 12

Egeria 49 Eichhornia9, 21, 45

Eleocharis 49

elegans 49

Gleichenia Smith 30

Glossopteris Brongniart 31

Heteranthera 62

Himantopus mexicanus (M?ller) 24

Hippuris 6

Hydrangea Linnaeus 31

Hydrocharis 9, 13

Hydrocleys 6

Hydropterangium Halle 31

Hymenachne

amplexicaule (Rudge) Nees 45

Hymenophyllaceae 30

Isoetes

lithophila Pfeiffer 69 Juncus 6

Lemma Jussieu ex Adanson 33

quadrifolia (Linnaeus) Desrousseaux in La

marck & Poiret33, 35

Lilaeopsis 14

Limnobium 9

Limnocharis 6

Loxsoma R. Brown ex A. Cunningham 30

Ludwigia 45, 49, 62

Lygodium Swartz 30, 31

Marsilea Linnaeus 33

sect. Clemys D. M. Johnson 14, 18, 20, 21,

22, 28, 31, 40, 42

sect. Marsilea 14, 28, 35, 73

sect. Nodorhizae D. M. Johnson 14, 20, 22,

28, 29, 48, 63

sect. Zalusianskaya (Necker) Alderwerelt 40

aegyptiaca Willdenow 3

ancylopoda A. Braun 3, 7, 8, 11, 13, 14, 15,

16, 18, 20, 21, 24, 25, 26, 28, 29, 34, 41,

48-53, 58, 59, 69, 71, 73, 79

angustifolia R. Brown 3, 15

bendirei Ward 31

berhautii Tardieu 13, 28, 40, 43

berteroi A. Braun 3, 48, 53, 59

biloba Willdenow 3

botryocarpa F. Ballard 13, 17

brachycarpa A. Braun 3

brachypus A. Braun 3

brasiliensis Martius 44, 46

brownii A. Braun 3, 19, 28, 38, 62

burchellii (Kunze) A. Braun 3

capensis A. Braun 3, 73

caribaea 46

concinna Baker 48, 53

cornuta (A. Braun) A. Braun 3

coromandeli^a Willdenow 3

crenata Presl 15, 79

crenulata Desvaux 3

crotophora D. M. Johnson 7, 8, 9, 11, 13, 16,

21, 22, 23, 28, 31, 34, 42, 43, 46-47, 48, 79

crotophora x deflexa 22, 48, 79

deflexa A. Braun 3, 6, 7, 8, 9, 11, 13, 15, 16,

20, 21, 22, 23, 25, 26, 33, 40-43, 44, 46,

47, 48, 79

deflexa x polycarpa 22, 34, 42, 43, 47-48, 79

diffusa Leprieur ex A. Braun 3, 28

distorta A. Braun 3, 18, 28, 52




drummondii A. Braun 3, 7, 9, 15, 17, 25

elata A. Braun 3

ephippiocarpa Alston 25, 26, 79

ernestii A. Braun 3, 48, 53, 59

erosa Willdenow 3, 28

exarata A. Braun 3, 73

farinosa Launert 17

fournieri C. Christensen 63, 69

gibba A. Braun 3, 79

glomerata Launert 17

glomerata Presl 17

gracilenta A. Braun 3

gymnocarpa Leprieur ex A. Braun 3

heterophylla 60

hickenii Herter 49, 53

hirsuta R. Brown 3

hirsutissima A. Braun 3

holtingiana 60

howittiana A. Braun 3

longipes Austin 74

macra A. Braun 3

macrocarpa Presl 3

macropoda Engelmann ex A. Braun in Kunze

3, 7, 8, 9, 11, 12, 15, 16, 18, 20, 21, 22,

23, 24, 25, 28, 34, 38, 50, 56, 60-62, 63,

70, 73, 79

macropoda x vestita 15, 16, 22, 34, 62, 70,

73,79 megalomanica Launert 17

mexicana A. Braun 3, 15, 16, 17, 48, 53, 59

minuta E. Fournier 39, 63

minuta Linnaeus 7, 8, 11, 13, 15, 16, 18, 20,

25, 26, 27, 28, 34, 35, 38, 39-40, 51, 63,

68,79 mollis Robinson & Fernald 7, 8, 11, 14, 15,

16, 18, 24, 25, 28, 34, 51, 53, 55, 57-60,

63, 64, 67, 69, 79

mucronata A. Braun 3, 28, 63, 68

var. antrorsa 63

muelleri A. Braun 3

muscoides A. Braun 3

mutica Mettenius 3, 10, 19, 28, 38, 59, 62

nardu A. Braun 3

nashii Underwood in Britton 8, 11, 15, 16,

17, 18, 34, 51, 55, 63, 69, 70-71, 79

natans Linnaeus 39

nubica A. Braun 3

oligospora Goodding 8, 11, 16, 18, 21, 28, 35,

53-57, 59, 63, 64, 67, 79

oxaloides A. Braun 3

petularia 60

picta F?e 60

polycarpa Hooker & Greville 3, 8, 9, 11, 16,

17, 22, 23, 28, 34, 40, 42, 43, 44-46, 47,

48, 71, 79

var. mexicana A. Braun 3, 44

pubescens Tenore 3

punae Sota 57

quadrata A. Braun 3

quadrifolia Linnaeus 3, 8, 10, 11, 13, 14, 15,

16, 18, 19, 25, 26, 27, 28, 33, 34, 35-39,

40, 62, 79

rotundata A. Braun 3

salvatrix Hanstein 3

sericea A. Braun 3

stratiotes 47

striata Mettenius 40, 43

strigosa Willdenow 3, 10, 17

xsubangulata A. Braun 3, 22, 23, 34, 42, 43,

48,79 subterr?nea A. Braun 3, 18, 28, 40, 52

tenuifolia Engelmann ex A. Braun in Kunze

3, 15, 16, 69

trichopoda A. Braun 3

uncinata A. Braun ex A. Braun 3, 63, 68, 69

var. texana 63

vera Jarmolenko 18

vera Launert 18, 28, 52

vestita Hooker & Greville 3, 8, 13, 14, 18,

19, 22, 23, 24, 25, 38, 48, 51, 55, 57, 59,

62-70, 71, 72, 73, 79

subsp. tenuifolia (Engelmann ex A. Braun) D. M. Johnson 15, 16, 34, 55, 69-70, 79

subsp. vestita 7, 10, 11, 15, 16, 20, 25, 27,

34, 55, 56, 63-69, 70, 79

var. minima A. Braun 63, 69

var. mucronata (A. Braun) Baker 63

var. tenuifolia (Engelmann ex A. Braun) Underwood & Cook 69

var. uncinata (A. Braun) Baker 63

villosa Kaulfuss 3, 8, 34, 55, 63, 72-73, 79

Mecodium Presl ex Copeland 30

Meringium Presl 30

Mimosa 45

Molaspora Schemel 31, 32

Najas 41, 49

Nelumbo 25

Neptunia 41

oler?cea Loureiro 45

Notholaena

sinuata (Lagasca) Kaulfuss 9

Nuphar 6, 13

Nymphoides 9, 13, 45

Onoclea Linnaeus 30

Ottelia 6

Oxyura australis Gould 24

Panicum 62

Paspalum 49

Peltandra

virginica 27

Phyla 49 Pilularia Linnaeus 1, 6, 8, 9, 14, 29, 30, 31

americana A. Braun 9, 12




Pistia 9, 49

Polygonum 62

amphibium 12

Proserpinaca

palustris 12

Psaronius Cotta 6

Pteridium Gleditsch ex Scopoli 30

aquilinum (Linnaeus) Kuhn 9 Recurvirostra

americana Gmelin 24

Regnellidium Lindman 1, 6, 7, 9, 10, 12, 14, 29, 31

diphyllum Lindman 6, 8, 9

Rhus 24 Rodeites Sahni 31

polycarpa (Chitaley & Paradkar) Chitaley & Paradkar 6

Sagittaria 6, 9, 63

Salvinia Seguier 30, 39, 45, 49

Scheuchzeria 6

Schizaea Smith 29, 31

pusilla Pursh 29 robusta Baker 29

rupestris R. Brown 29

Schizaeaceae 29, 30

Scirpus cubensis Kunth 45

Sium

suave 12

Sparganium 6

eurycarpum 27

Spodoptera

exigua (H?bner) 27 litura (Fabricius) 27

Stictonetta

naevosa (Gould) 24

Stratiotes 13

Thalia 49

Thelypteris Schmidel 30 Trichomanes Linnaeus 30

radicans Swartz 31

Utricularia 41

Woodsia

ilvensis (Linnaeus) R. Brown 9

Woodwardia Smith 30

Zaluzianskia Necker 33

ancylopoda (A. Braun) Kuntze 48

berteroi (A. Braun) Kuntze 48

concinna (Baker) Kuntze 48

deflexa (A. Braun) Kuntze 40

ernestii (A. Braun) Kuntze 48

macropus (A. Braun) Kuntze 60

marsiloides Necker 33, 35

mexicana (A. Braun) Kuntze 48

polycarpa (Hooker & Greville) Kuntze 44

quadrifolia (Linnaeus) Kuntze 35

tenuifolia (Engelmann ex A. Braun) Kuntze 69

vestita (Hooker & Greville) Kuntze 62

villosa (Kaulfuss) Kuntze 72

Zaluzianskya F. W. Schmidt 33

Zizania

aquatica 12



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