The Monocots: Part 2Commelinoid Monocots

Spring 2010

Phylogeny of Monocot Groups

AcoralesAlismatalesAsparagalesLilialesDioscorealesPandanalesArecalesPoalesCommelinalesZingiberales

Basal“Petaloid”Commelinoid

Commelinoid characters

• Special type of epicuticular wax

• Starchy pollen

• UV-fluorescent compounds in the cell walls

• Starchy endosperm (except in the palms)

• Lots of molecular support

Commelinoid Monocot Groups

Order Arecales - PalmsArecaceae (Palmae)

Order Poales - Grasses - Bromeliads Cat-tails Rushes, Sedges, and GrassesBromeliaceaeTyphaceaeJuncaceae CyperaceaePoaceae (Gramineae)

Order Zingiberales – Ginger, banana, and allies (no required families)

Commelinoid Monocots:

Arecales: Arecaeae (Palmae)• Widespread throughout tropical and warm temperate

regions

• “Trees” or “shrubs”, typically unbranched

• Diversity: ca. 2,780 in 200 genera

• Flowers: usually sessile, in compound-spicate inflorescences, these subtended by a bract (spathe); ovule 1 per locule

• Significant features: Leaves alternate or spiral, blades plicate, splitting in a pinnate or palmate manner

• Special uses: coconut (Cocos nucifera), date (Phoenix dactylifera), rattan (Calamus), oils and waxes, ornamentals

• Required taxa: *family only* Change from lab manual

Arecaceae

•Unbranched trunks•Big leaves on top!

•Numerous small flowers•Spathes + compound-spicate inflorescence•3 sepals + 3 petals•Superior ovary (carpel fusion varies)•Drupe

Arecaceae – The Palm Family

Arecaceae – Cocos nucifera

ArecaceaeEconomic plants and products:

Phoenix dactyliferaDates

Characters of Poales• Silica bodies (in silica cells) in the

epidermis

• Styles strongly branched

• Loss of raphide (needle-like) crystals

• Much molecular support for monophyly

• Wind pollination has evolved several times independently within the order

• Ecologically very important

Commelinoid Monocots—Poales:

Bromeliaceae(The Pineapple/Bromeliad Family)

• Tropical to temperate regions of the Americas• Predominantly epiphytic herbs (“tank” plants)• Diversity: ca. 1,520 species in 51 genera• Flowers: radial, perianth differentiated into

calyx and corolla, borne in axils of often brightly colored bracts; inflorescences spicate or paniculate; stigmas 3, usually twisted; seeds often winged or with tufts of hair

• Significant features: leaves with water absorbing peltate (or stellate) scales

• Special uses: pineapple (Ananas)• Required taxa: *Tillandsia (Spanish moss)

*change from lab manual*change from lab manual

Bromeliaceae

Bromeliaceae: Tillandsia(Spanish moss)

Bromeliaceae – Ananas comosus

Fruittype?

Commelinoid Monocots—Poales:

Typhaceae(The Cattail Family)

• Widely distributed, especially in Northern Hemisphere

• Aquatic & wetland rhizomatous herbs• Diversity: 28 species in 2 genera• Flowers: small, unisexual; separated spatially

on dense, compact spicate or globose-clustered inflorescences; placentation apical

• Significant features: rhizomatous; long slender leaves; characteristic inflorescence

• Special uses: ornamental aquatics• Required taxa: Typha

Typhaceae - Typha

Commelinoid Monocots—Poales:

Juncaceae(The Rush Family)

• Worldwide, mostly temperate regions; wet or damp habitats

• Rhizomatous herbs, stems round and solid

• Diversity: 400 species in 6 genera

• Flowers: tepals 6, distinct; carpels 3 in superior ovary; stamens 6; fruit a loculicidal capsule

• Significant features: leaves 3-ranked, sheaths usually open

• Special uses: leaves used to weave rush baskets; some ornamentals

• Required taxa: Juncus

Juncaceae

Juncaceae: Juncus

-cymose inflorescences-leaf sheaths open-leaf blades flat, grooved, or cylindrical

Commelinoid Monocots—Poales:

Cyperaceae(The Sedge Family)

• Worldwide, usually in damp or semi-aquatic sites• Rhizomatous herbs, stems usually triangular in

cross section• Diversity: 4,500 species in 104 genera• Flowers: with subtending bract; tepals absent or

reduced to 3-6 scales or hairs; stamens 1-3; carpels 2-3 in superior ovary; fruit an achene (nutlet)

• Significant features: Inflorescence a complex group of spikelets; leaf sheaths closed, ligule lacking; silica bodies conical

• Special uses: Papyrus used originally for paper; “water chestnuts”and a few other rhizomes edible, leaves used for weaving; some ornamentals.

• Required taxa: Carex, Cyperus

Cyperaceae versus Juncaceae:Field Character

“Sedges have edges…

…and rushes roll.”

Cyperaceae

Cyperaceae

spikelet

flower + subtending bract = floret

Flowers:•Arranged in spikelets•Reduced•Wind-pollinated flowers•Subtended by bract•Reduced/absent perianth

flower

Cyperaceae

Cyperus

Eleocharis Rhynchospora(note bristle perianth)

Fruit type is the achene: very important inthe taxonomy of the family.

Cyperaceae: Cyperus

Cyperaceae: Carex

-presence of the perigynium (a sac-likebract surrounding the female flower) in addition to the subtending bract-leaves usually with a ligule

Commelinoid Monocots—Poales:

Poaceae (Gramineae)(The Grass Family)

• Cosmopolitan• Primarily herbs, often rhizomatous; “trees” in most

bamboos; stems are called culms• Diversity: 10,000 species in ca. 650 genera• Flowers: small, perianth parts reduced to lodicules;

each flower enclosed by two bracts (lemma and palea) = floret; stamens typically 3; carpels 3, but appearing as 2; fruit a caryopsis

• Significant features: 1-many florets aggregated into spikelets, each with usually 2 empty bracts (glumes) at the base; leaf with a ligule

• Special uses: many – grains, turf, fodder/forage, structural uses (e.g., bamboo).

• Required taxa: *Poa, *Andropogon

*change from lab manual

Economicimportance Zea mays

Oryza sativaTriticum aestivum

weeds

sugar cane

bamboo

Ecologicalimportance

Poaceae: vegetative structure

ligule

Poaceae: spikelet and flower structure

flower

• The fruit wall (pericarp) is completely fused to the seed coat.

• Endosperm (3N; triploid) contains the bulk of starch storage in the seed.

• The embryo is a pre-formed grass plant, with apical meristems (for both shoot and root) and protective organs (coleoptile and coleorhiza) which emerge first during germination.

Anatomy of the

Caryopsis (Grain)

Origin of grassesca. 70-80 myain southern-hemisphereforests

early grasses

Panicgrasses(Panicoideae)

Rices(Ehrhartoideae)

Bluegrasses(Pooideae)

Bamboos(Bambusoideae)

Puelioideae

PharoideaeAnomochlooideae

Needlegrasses(Aristidoideae)

Lovegrasses(Chloridoideae)

Micrairoideae

Reeds(Arundinoideae)

Oatgrasses(Danthonioideae)

Major radiationin Oligocene-Miocene epochsinto open habitats

Origin of grassesca. 70-80 myain forests

+

Stamensreduced to 3

C4 photosynthetic pathway(in warm season grasses)is advantageous under higher temperatures, higherlight, and less water

Dispersal!

Poaceae (Gramineae)

Poaceae: Poa -cool season-leaf tip boat-shaped-inflorescence branched from a main axis-spikelets solitary-glumes papery-florets 3-several, often with a cottony web at the base

Poaceae: Andropogon-warm season-leaf midrib whitish, prominent-2-many branches per inflorescence, often digitate-spikelets paired-glumes tough, leathery

For more informationand images:

http://www.eeob.iastate.edu/research/iowagrasses/

The Grasses of Iowa

Grasses, Sedge, Rushes!•Stem terete, hollow, or solid, jointed

•Leaf ranks 2

•Leaf sheath Open, ligule

•Inflor: Spikelets

•Perianth: Lodicules

•Fruit: Caryopsis

•Triangular, solid, not jointed

•3

•Closed

•Spikelets

•None or bristles/scalesAchene

•Terete, solid, not jointed

•3

•Open

•Cymose

•6 chaffy tepals

•Capsule

“Graminoids” - Comparison

Commelinales 5 families, 780 species, widespread in

various habitats

Commelinoid Monocots: Zingiberales

• Large herbs with vessels more or less limited to the roots

• Silica cells present in the bundle sheaths• Leaves clearly differentiated into a petiole and blade• Leaf blade with pinnate venation, often tearing

between the second-order veins• Leaf blade rolled into a tube in bud• Petiole with enlarged air canals• Flowers bilateral (or irregular)• Pollen lacking an exine• Ovary inferior• Seeds arillate and with perisperm• 8 families and nearly 2000 species

Must be ableMust be ableto recognizeto recognizethe order!the order!

Zingiberalesdiversity

MusaceaeMusa