phylum pteridophyta (true ferns) - part 2
TRANSCRIPT
Pterophyta(True Ferns)SYNONYMS: PTERIDOPHYTA; FILICOPHYTA
STRUCTURE and FORM
approximately 11,000 known species Vary in size from less than 1 cm in diameter to 25 meters
tallFern leaves are megaphylls that are commonly referred
to as fronds
STRUCTURE and FORM
Some are undivided, pleated or tongue-like, and others resemble four-leaf clover or grow in such a way as to form “nests”
Most abundant in wetter tropical and temperate habitats but few are adapted to drier areas
STRUCTURE and FORM
Early leaves are lopsided because they grow faster on their lower surface than their upper surface. This growth pattern, which is called circinate vernation, produces young leaves that are coiled into “fiddle heads.”
These croziers or “fiddle heads” the unroll and expand revealing the blades.
Fern leaves are usually fertile but do not form strobili.
FIDDLE HEADS
STRUCTURE and FORM
Sorus- dark spots on the lower surface of fern leaves which is actually a collection of sporangia
These patches appear similar to fungal rustsSori of some species are covered by an outgrowth from the leaf
surface called indisiumMost modern ferns are homosporous (two orders of water ferns
and some extinct ferns are heterosporous).
A and B. Cross-section through a leaflet of a true fern 1 = frond, 2 = vascular bundle, 3 = sorus, 4 = indusium (protective scale), 5 = sporangia, 6 = sporangium wall, 7 = spores C. Detail of an entire spore D. Detail of section through spores. E. Detail of the wall of a spore
STRUCTURE and FORM
The more primitive species have a protostele, most have siphonosteles, and some have complex dictyosteles.
Stems, for the most part, are rhizomes that grow at, or just under, the ground surface.
Roots are simple, uncomplicated and arise adventitiously along the rhizomes near the base of the fronds.
STRUCTURE and FORM
Ferns are divided into two groups based on the kind of sporangium they possess. The more primitive are the eusporangiate, and the more advanced the leptosporangiate.
Eusporangia: These sporangia are thick walled and open by ‐splitting transversely. They produce thousands of spores.
STRUCTURE and FORM
Leptosporangia: These thin walled, delicate sporangia ‐are only one or a few layers thick. They have an area, the annulus, where cell walls are thickened. When the annulus cells dry out at maturity, the sporangium splits and, like a catapult, throws out the spores.
Spores are few—128 at most, but commonly 64.
REPRODUCTION
Sporophyte – is the conspicuous phase of the life cycleFern’s sporophyte consist of the fronds, a stem in the
form of a rhizome, and adventitious roots that arise along the rhizome.
Young sporophyte and gametophyte
REPRODUCTION
At maturity, the blades are often divided into segments called pinnae that are attached to a midrib or rachis.
A stalk or petiole is usually present at the base.Sori appear on the lower surfaces of blades of a mature
fronds.
REPRODUCTION
o These patches are actually clusters of sporangia.oThese are mostly found in numerous, discrete clusters called
sori (singular:sorus)oThe sori are protected by thin, individual flaps of colorless
tissue called indusia (singular:indusium)oThis indisium often resembles a tiny, semi-transparent
umbrella attached to its base to the frond surface
REPRODUCTION
oAs sporangia mature, the indisium, resembles shrivels and exposes the sporangia beneath.
Most sporangia have a conspicuous row of heavy-walled brownish cells along the edge. This row of cells is called annulus which looks like a tiny millipede.
Annulus functions in catapulting spores out of the sporangium.
REPRODUCTION
Annulus functions in catapulting spores out of the sporangium.
Sporocytes undergo meiosis in the sporangia producing either 48 or 64 spores per sporangium
After the spores have been flung out of their sporangia, they are dispersed by the wind
REPRODUCTION
Shady, wet ledges and rock crevices or moist soil are habitats usually suitable for their survival
Those that germinate in favorable locations produce little “Irish valentines” or prothalli as the green, heart-shaped gametophytes of ferns and other seedless vascular plants
Prothalli are only one cell thick except the middle which is slightly thicker
1 = young prothallium, 2 = rest of the spore wall, 3 = chloroplasts, 4 = rhizoids
REPRODUCTION
Antheridia are interspersed among the rhizoids produced on the lower surface of the central area with archegonia are also being produced, usually closer to the notch of the heart-shaped gametophyte.
Archegonia – flask-shaped with curving necks that protrude slightly above the surface
A - D. Prothallium with antheridia. Zoom view of antheria and sperms. A and B. 1 = antheridia, 2 = sperms in the antheridia C. Detail of sperms (with flagella) D. Detail of antheridia filled up with sperms
A - D. Prothallium with archegoniaZoom view of prothallium, archegonia and egg cell A. Prothallium with archegonia B. Detail of archegonium in a cross-section (zoom of archegoniuma, egg cell) C. Detail of archegonia in upperview D. Detail of prothallium cells (photosynthetic active due to chloroplasts) 1 = prothallium, 2 = prothallium cells, 3 = rhizoids, 4 = archegonia, 5 = egg cell, 6 = neck canal cells, 7 = neck canal, 8 = chloroplasts inside prothallium cells, 9 = cell nucleus
FAMILY: Schizaeaceae
leaves more or less grasslike, with a long petiole and a linear or fan-shaped blade
veins dichotomously branchingsporangia dense on specialized slender lobes of the
ultimate segmentsmostly tropical
FAMILY: SchizaeaceaeGENUS: Schizaea
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: SchizalesFamily: Schizaeaceae
Genus: Schizaea
FAMILY: SchizaeaceaeGENUS: Schizaea
Common names: curly grass and comb fernSome species are very small and inconspicuous, and so
may often be overlooked in natureThe genus is distinctive and not at all like the common
conception of a fern
Schizaea pectinata
FAMILY: SchizaeaceaeGENUS: Actinostachys
small genus of small ferns originally included in the genus Schizaea
was segregated on the basis of the flabelliform (fan-shaped) laminae
colloquially called the ray ferns.
Actinostachys laevigata
FAMILY: Thelypteridaceae
plants in soil or, less commonly, on rocksrhizomes short- to long-creeping or erect, scalyleaves mostly one or two times pinnately divided, rarely
highly divided, most commonly with slender needlelike hairs sori round or elongate along the veins, the indusia absent or
kidney-shaped
FAMILY: ThelypteridaceaeGENUS: Thelypteris
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: PolypodialesFamily: Thelypteridaceae Genus: Thelypteris
FAMILY: ThelypteridaceaeGENUS: Thelypteris
“maiden ferns”terrestrial, with the exception of a few which are
lithophytes (grow on rocks)hese ferns are tropical, although there are a number of
temperate species
Thelypteris palustris
FAMILY: ThelypteridaceaeGENUS:Phegopteris
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: ArthyrialesFamily: Thelypteridaceae Genus: Phegopteris
Phegopteris connectilis
FAMILY: Dicksoniaceae
tree fern familystems mostly erect and trunklike (up to 10 m or 33 ft.) or,
less commonly, smaller, hairy near the tip and usually with a mantle of roots
leaves, which are often highly divided (up to 3.5 m. or 11.5 ft.)
FAMILY: Dicksoniaceae GENUS: Dicksonia
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: CyathealesFamily: Dicksoniceae Genus: Dicksonia
FAMILY: Dicksoniaceae GENUS: Dicksonia
regarded as related to Cyathea, but is considered more primitive
fossil record includes stems, pinnules, and spores.An easily cultivated species of Dicksonia is D. antarctica,
the soft tree fern
Dicksonia fibrosa
FAMILY: Hymenophyllaceae
“filmy ferns” and “bristle ferns”often appear as very dark green or even black clumps
and may be mistaken for a robust moss or liverwortsmostly rainforest epiphytesspores globose, greengametophyte ribbon-shaped or filamentous
FAMILY: Hymenophyllaceae GENUS: Hymenophyllum
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: HymenophyllalesFamily: Hymenophyllaceae Genus: Hymenophyllum
FAMILY: Hymenophyllaceae GENUS: Hymenophyllum
its name means "membranous leaf", referring to the very thin translucent tissue of the fronds
leaves are generally only one cell thick and lack stomata, making them vulnerable to desiccation
found only in very humid areas, such as in moist forests and among sheltered rocks
Hymenophyllum tunbrigense
FAMILY: Hymenophyllaceae GENUS: Trichomanes
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: HymenophyllalesFamily: Hymenophyllaceae Genus: Trichomanes
FAMILY: Hymenophyllaceae GENUS: Trichomanes
termed bristle fernsleaf tissue typically 2 cells thickthe name bristle fern refers to the small bristle that
protrudes from the indusia of these ferns
Trichomanes radicans
FAMILY: Blechnaceae
plants in soil or on rocks, less commonly epiphytic, rarely climbing
rhizomes short- to long-creeping or erect (occasionally trunklike), scaly
leaves one time pinnately compound or lobeddistributed nearly worldwide but most diverse in tropical
regions
FAMILY: BlechnaceaeGENUS: Blechnum
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: PolypodialesFamily: Blechnaceae Genus: Blechnum
FAMILY: BlechnaceaeGENUS: Blechnum
“hard fern”greatest species diversity is in tropical regionsmost are herbaceous plants, but a few species are tree
ferns with stems up to 3 m tallvaries from most ferns in having a separation of sterile
(photosynthetic) and fertile (reproductive) fronds in the same plant.
Blenchum brasiliense
FAMILY: Cyatheacea
scaly tree fern familystems erect and mostly trunklike (up to 25 m. or 82 ft.)scaly near the tip (sometimes also hairy) and usually with
a mantle of rootsleaves mostly large (up to 5 m. or about 16 ft.), one to
four times pinnately compound
FAMILY: CyatheaceaGENUS: Cyathea
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: CyathealesFamily: Cyatheaceae Genus: Cyathea
FAMILY: CyatheaceaGENUS: Cyathea
terrestrial ferns, usually with a single tall stemrarely, the trunk may be branched or creepingmany species also develop a fibrous mass of roots at the
base of the trunkhabitats ranging from tropical rain forests to temperate
woodlands
Cyathea
FAMILY: Aspleniaceae
“spleenworts”plants in soil, on rocks, or epiphyticrhizomes short- to long-creeping or erect, usually scaly,
the scales usually clathrate (the cells with dark adjoining walls and clear lateral walls)
the spores are mostly bean-shaped (bilateral)
FAMILY: Aspleniaceae GENUS: Asplenium
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: PolypodialesFamily: Aspleniaceae Genus: Asplenium
Asplenium
FAMILY: Dennstaedtiaceae
“cup ferns” and “bracken”mostly in soil, occasionally climbingrhizomes mostly very long-creeping (to more than 100 m.
or 330 ft.), in Pteridium), hairyleaves two to four times pinnately compound, glabrous
or hairy
FAMILY: DennstaedtiaceaeGENUS: Pteridium
Kingdom: Plantae
Division: PteridophytaClass: PolypodiopsidaOrder: Dennstaedtiales
Family: DennstaedtiaceaeGenus: Pteridium
FAMILY: DennstaedtiaceaeGENUS: Pteridium
“bracken”noted for their large, highly divided leavesthe world's most abundant fern
Pteridium aquilinum
FAMILY: Salviniaceae
heterosporous fernsfloating fernsmostly appearing dichotomously branched, sometimes
lacking rootsdistributed nearly worldwide but most diverse in the
tropics.
FAMILY: SalviniaceaeGENUS: Salvinia
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: SalvinialesFamily: Salviniaceae
Genus: Salvinia
FAMILY: SalviniaceaeGENUS: Salvinia
“watermoss”small, floating aquatics with creeping stems, branched,
bearing hairs on the leaf surface papillae but no true rootsleaves are in trimerous whorls, with two leaves green,
sessile or short-petioled, flat, entire, and floating, and one leaf finely dissected, petiolate, rootlike, and pendent
Salvinia minima
FAMILY: SalviniaceaeGENUS: Azolla
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: SalvinialesFamily: Salviniaceae
Genus: Azolla
FAMILY: SalviniaceaeGENUS: Azolla
“mosquito fern, duckweed fern, fairy moss”extremely reduced in form and specialized, looking
nothing like other typical ferns but more resembling duckweed or some mosses
Azolla filiculoides
FAMILY: Marsileaceae
"pepperwort family" or "water-clover family"heterosporousaquatic and semi-aquatic ferns, though at first sight they
do not physically resemble other ferns
FAMILY: MarsileaceaeGENUS: Marsilea
Kingdom: PlantaeDivision: Pteridophyta
Class: PolypodiopsidaOrder: SalvinialesFamily: Marsileaceae
Genus: Marsilea
FAMILY: MarsileaceaeGENUS: Marsilea
aquatic fernsunusual appearance and do not resemble common ferns“water clover” or “four-leaf clover” because the long-
stalked leaves have four clover-like lobes and are either held above water or submerged.
Marsilea
USESsome ferns species are edible, with crosiers being
considered delicaciesOther ferns are used medicinallyby contrast, Osmunda and Pteridium ferns are
considered to be carcinogenic (any substance or agent that tends to produce a cancer)
USESthe aquatic mosquito fern (Azolla) hosts Anabaena
azollae, which converts nitrogen for use by plants such as rice, enhancing production in rice paddies and other fields
animals often root for fern rhizomes, which store starches
USESthe braken fern Pteris vittata absorbs arsenic, a
carcinogenic heavy metal, from soil. By removing this toxin, ferns can restore contaminated areas into viable agricultural, industrial, and recreational sites.
ornamental garden plants and houseplants