The Monocots: Part 2 Commelinid Monocots

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The Monocots: Part 2Commelinid Monocots

Spring 2013

Phylogeny of Monocot GroupsAcoralesAlismatalesAsparagalesLilialesDioscorealesPandanalesArecalesPoalesCommelinalesZingiberales

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

Commelinid Monocot GroupsOrder Arecales – Palms

Arecaceae (Palmae)

Order Commelinales – Spiderworts, bloodworts, pickerel weeds

Order Zingiberales – Ginger, banana, and allies

Order Poales – Bromeliads, Cat-tails, Rushes, Sedges, and GrassesTyphaceae*Juncaceae* Cyperaceae*Poaceae (Gramineae)*

*required families

Commelinoid Monocots:Arecales: Arecaeae (Palmae)

• Widespread throughout tropical and warm temperate regions

• “Trees” or “shrubs”, typically unbranched• Diversity: ca. 2,000 species 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 – Cocos nucifera

ArecaceaeEconomic plants and products:

Cocos nuciferaCoconut, oil

ArecaceaeEconomic plants and products:

Phoenix dactyliferaDates

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, mainly tropical• Not required

Fig. 7.55

Zingiberalesdiversity

Fig. 7.56

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 extremely important

Fig. 7.63

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

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

Commelinid Monocots—Poales: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

-important in manywetland habitats

Commelinid Monocots—Poales: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

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 • Subtended by one bract• Reduced/absent perianth

flower

From Zomlefer 1994

Cyperaceae

CyperusEleocharis Rhynchospora(note bristle perianth)

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

Cyperaceae

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

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

Commelinid Monocots—Poales:Poaceae (Gramineae)

(The Grass Family)• Cosmopolitan• Primarily herbs, often rhizomatous; “trees” in most

bamboos; stems are called culms, hollow or solid• Diversity: >11,000 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 family

Economicimportance Zea mays

Oryza sativaTriticum aestivum

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)

PuelioideaePharoideaeAnomochlooideae

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: Bamboos

Oryza (rice)

Triticum (wheat)

Zea (maize or corn)

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/scales

Achene

• Terete, solid, not obviouslyjointed

• 3• Open

• Cymose

• 6 chaffy tepals

• Capsule

“Graminoids” - Comparison

Next time: The “Basal” Eudicots…

The Monocots: Part 2 Commelinid Monocots

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