The Monocots: Part 2 Commelinid Monocots Spring 2012.

The Monocots: Part 2The Monocots: Part 2Commelinid MonocotsCommelinid Monocots

Spring 2012

Phylogeny of Monocot Groups

AcoralesAlismatalesAsparagalesLilialesDioscorealesPandanalesArecalesPoalesCommelinalesZingiberales

Basal“Petaloid”Commelinid

Fig. 7.17

Commelinid 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

Fig. 7.45

Commelinoid Monocot Groups

Order Arecales – PalmsArecaceae (Palmae)

Order Commelinales – Spiderworts, bloodworts, pickerel weeds

Order Zingiberales – Ginger, banana, and allies

Order Poales – Bromeliads, Cat-tails, Rushes, Sedges, and GrassesTyphaceaeJuncaceae CyperaceaePoaceae (Gramineae)

Commelinoid Monocots:

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

regions

• “Trees” or “shrubs”, typically unbranched

• Diversity: ca. 2,000 in 190 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

• Family not required

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 – Cocos nucifera

ArecaceaeEconomic plants and products:

Cocos nuciferaCoconut, oil

ArecaceaeEconomic plants and products:

Phoenix dactyliferaDates

Commelinales 5 families, ca. 780 species, widespread in

various habitats

Not required

Commelinid 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 penni-parallel 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 (diploid nutritive tissue derived

from the nucellus)• 8 families and nearly 2000 species

Fig. 7.55

Zingiberalesdiversity

Fig. 7.56

MusaceaeMusa

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

epidermis• Styles strongly branched• Loss of raphide (needle-like) crystals in

most• Much molecular support for monophyly• Wind pollination has evolved several

times independently within the order• Ecologically very important

Fig. 7.63

Commelinid Monocots—Poales:

Bromeliaceae(The Pineapple/Bromeliad Family)

• Tropical to temperate regions of the Americas• Predominantly epiphytic herbs (“tank” plants)• Diversity: ca. 2,400 species in 59 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)• Family not required

Bromeliaceae: Tillandsia(Spanish moss)

Bromeliaceae – Ananas comosus

Fruittype?

Commelinoid Monocots—Poales:

Typhaceae(The Cattail Family)

• Widely distributed, especially in Northern Hemisphere

• Emergent aquatic rhizomatous herbs• Diversity: 8-13 species in 1 genus• Flowers: small, unisexual; separated

spatially on dense, compact spicate inflorescences; placentation apical

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

• Special uses: ornamental aquatics• Required taxa: Typha

Sparganium

This genus is placed inits own family, theSparganiaceae, in yourtext, but it is closelyrelated to Typhaceae andis included in Typhaceaein many treatments.

Typha


Juncaceae(The Rush Family)

• Worldwide, mostly temperate regions; wet or damp habitats

• Rhizomatous herbs, stems round and solid

• Diversity: 350 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

Juncus

Distichia

Juncaceae: Juncus

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


Cyperaceae(The Sedge Family)

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

cross section and solid• Diversity: 5,000 species in 104 genera• Flowers: with 1 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.”

Fig. 7.65

Fig. 7.66D

Cyperaceae

Sedge spikelet

flower + subtending bract = floret

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

flower

From Zomlefer 1994

Cyperaceae

Cyperus

Eleocharis Rhynchospora(note bristle perianth)

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

Cyperaceae

http://waynesword.palomar.edu/termfl3.htm

Cyperaceae: Cyperus

-leaves usually basal-ligules absent-spikelet scales distichous, each subtending a flower-spikelets flattened or cylindrical-flowers bisexual-no perigynium

Cyperaceae: Carex

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

Cyperaceae: Carex


Poaceae (Gramineae)(The Grass Family)

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

bamboos; stems are called culms, hollow or solid• Diversity: >10,000 species in ca. 650 genera• Flowers: small petals 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: family only

Economicimportance Zea mays

Oryza sativaTriticum aestivum

weeds

sugar cane

bamboo

Ecologicalimportance

Poaceae: vegetative structure

ligule

Poaceae: spikelet and flower structure

flower

Images fromGrasses of Iowa

• 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)

Poaceae: caryopsis (grain)

Setariafoxtail

Zea mayscorn or maize

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: Bambusoideae

Oryza (rice)

-aquatic or wetland herbs-one floret per spikelet-spikelets strongly flattened

Triticum (wheat)-annuals-dense inflorescences-spikelets sessile, one per node-2-9 florets per spikelet

Zea (maize or corn)

-male and female spikelets usually on separate inflorescences-female inflorescences axillary, enclosed in 1 or more sheaths (husks), one sessile spikelet per node-male inflorescences terminal, with paired spikelets

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 obviously jointed•3

•Closed

•Spikelets

•None or bristles/scalesAchene

•Terete, solid, not obviouslyjointed

•3

•Open

•Cymose

•6 chaffy tepals

•Capsule

“Graminoids” - Comparison

Next time: Next time: The “Basal” Eudicots…The “Basal” Eudicots…

The Monocots: Part 2 Commelinid Monocots Spring 2012.

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