Commelinid Monocots
Spring 2012

Basal
“Petaloid”
Commelinid
Acorales
Alismatales
Asparagales
Liliales
Dioscoreales
Pandanales
Arecales
Poales
Commelinales
Zingiberales

Fig. 7.17

• 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

Order Arecales – Palms
Arecaceae (Palmae)
Order Commelinales – Spiderworts, bloodworts, pickerel weeds
Order Zingiberales – Ginger, banana, and allies
Order Poales – Bromeliads, Cat-tails,
Rushes, Sedges, and Grasses
Typhaceae
Juncaceae
Cyperaceae
Poaceae (Gramineae)

Commelinoid Monocots:
•
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

• Numerous small flowers
• Spathes + compound-spicate inflorescence
• 3 sepals + 3 petals
•
Superior ovary
(carpel fusion varies)
• Drupe
• Unbranched trunks
• Big leaves on top!

Arecaceae – Cocos nucifera

Economic plants and products:
Cocos nucifera
Coconut, oil

Economic plants and products:
Phoenix dactylifera
Dates

Basal
“Petaloid”
Commelinid
Acorales
Alismatales
Asparagales
Liliales
Dioscoreales
Pandanales
Arecales
Poales
Commelinales
Zingiberales

5 families, ca. 780 species, widespread in various habitats
Not required

•
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

Zingiberales diversity

Fig. 7.56

Musa

Basal
“Petaloid”
Commelinid
Acorales
Alismatales
Asparagales
Liliales
Dioscoreales
Pandanales
Arecales
Poales
Commelinales
Zingiberales

• 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:
(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 – Ananas comosus
Fruit type?

Commelinoid Monocots —Poales:
(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

Typha Sparganium
This genus is placed in its own family, the
Sparganiaceae, in your text, but it is closely related to Typhaceae and is included in Typhaceae in many treatments.

Commelinid Monocots —Poales:
(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

Distichia
Juncus

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

Commelinid Monocots —Poales:
(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

Fig. 7.66D
Fig. 7.65

Flowers:
• Arranged in spikelets
• Reduced
• Wind-pollinated flowers
• Subtended by bract
• Reduced/absent perianth
Sedge spikelet flower + subtending bract = floret flower
From Zomlefer 1994

Fruit type is the achene: very important in the taxonomy of the family.
Cyperus
Eleocharis Rhynchospora
(note bristle perianth)

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

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

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

Commelinid Monocots —Poales:
(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

bamboo sugar cane weeds
Economic importance Zea mays
Triticum aestivum
Oryza sativa

Ecological importance

ligule

Poaceae: spikelet and flower structure flower
Images from
Grasses 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.

Zea mays corn or maize
Setaria foxtail

Origin of grasses ca. 70-80 mya in southernhemisphere forests early grasses

Origin of grasses ca. 70-80 mya in forests
Major radiation in Oligocene-
Miocene epochs into open habitats
+
Stamens reduced to 3
Anomochlooideae
Pharoideae
Puelioideae
Bamboos
(Bambusoideae)
Bluegrasses
(Pooideae)
Rices
(Ehrhartoideae)
Panicgrasses
(Panicoideae)
Needlegrasses
(Aristidoideae)
Lovegrasses
(Chloridoideae)
Micrairoideae
Reeds
(Arundinoideae)
Oatgrasses
(Danthonioideae)

C
4 photosynthetic pathway
(in warm season grasses) is advantageous under higher temperatures, higher light, 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

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

!
•
Stem terete, hollow, or solid, jointed
• Leaf ranks 2
• Triangular, solid, not obviously jointed
•
3
•
Terete, solid, not obviously jointed
• 3
•
Leaf sheath Open, ligule
•
Closed
• Open
•
Inflor: Spikelets
•
Spikelets
•
Cymose
•
Perianth: Lodicules
• Fruit: Caryopsis
•
None or bristles/scales
Achene
• 6 chaffy tepals
•
Capsule

“Graminoids” - Comparison