1. The Monocots: Part 2 Commelinoid Monocots
Spring 2010

2. Phylogeny of Monocot Groups
Acorales
Alismatales
Asparagales
Liliales
Dioscoreales
Pandanales
Arecales
Poales
Commelinales
Zingiberales
Basal
“Petaloid”
Commelinoid

3. 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

4. Commelinoid Monocot Groups
Order Arecales - Palms
Arecaceae (Palmae)
Order Poales - Grasses - Bromeliads Cat-tails Rushes, Sedges, and Grasses
Bromeliaceae
Typhaceae
Juncaceae
Cyperaceae
Poaceae (Gramineae)
Order Zingiberales – Ginger, banana, and allies (no required families)

5. 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

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

7. Arecaceae – The Palm Family

8. Arecaceae – Cocos nucifera

9. Arecaceae
Economic plants and products:
Phoenix dactylifera
Dates

10. 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

11. 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

12. Bromeliaceae

13. Bromeliaceae: Tillandsia (Spanish moss)

14. Bromeliaceae – Ananas comosus
Fruit
type?

15. 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

16. Typhaceae - Typha

17. 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

18. Juncaceae

19. Juncaceae: Juncus -cymose inflorescences -leaf sheaths open
-leaf blades flat, grooved,
or cylindrical

20. 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

21. Cyperaceae versus Juncaceae: Field Character
“Sedges have edges… …and rushes roll.”

22. Cyperaceae

23. Cyperaceae Flowers: Arranged in spikelets Reduced
Wind-pollinated flowers
Subtended by bract
Reduced/absent perianth
flower + subtending bract = floret
flower
spikelet

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

25. Cyperaceae: Cyperus

26. Cyperaceae: Carex -presence of the perigynium (a sac-like
bract surrounding the female flower) in
addition to the subtending bract
-leaves usually with a ligule

27. 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

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

29. Ecological
importance

30. Poaceae: vegetative structure
ligule

31. Poaceae: spikelet and flower structure

32. Anatomy of the Caryopsis (Grain)
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.

33. Origin of grasses ca. 70-80 mya in southern- hemisphere forests
early grasses
Origin of
grasses
ca mya
in southern-
hemisphere
forests

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

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

36. Dispersal!

37. Poaceae (Gramineae)

38. 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

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

40. For more information and images: http://www. eeob. iastate
For more information and images: The Grasses of Iowa

41. 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/scales
Achene
Terete, solid,
not jointed 3
Open
Cymose
6 chaffy tepals
Capsule

42. “Graminoids” - Comparison

43. Commelinales
5 families, 780 species, widespread in various habitats

44. 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 able
to recognize
the order!

45. Zingiberales diversity

46. Musaceae Musa