1. The Monocots: Part 2 Commelinid Monocots
Spring 2013

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

3. Fig. 7.17

4. 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

5. Fig. 7.45

6. Commelinid Monocot Groups
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)*
*required families

7. 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

8. Arecaceae – Cocos nucifera

9. Arecaceae
Economic plants and products:
Cocos nucifera
Coconut, oil

10. Arecaceae
Economic plants and products:
Phoenix dactylifera
Dates

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

12. 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

13. Fig. 7.55

14. Zingiberales diversity

15. Fig. 7.56

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

17. 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

18. Fig. 7.63

19. Commelinoid Monocots—Poales: Typhaceae (The Cattail Family)
Widely distributed, especially in Northern Hemisphere
Emergent aquatic rhizomatous herbs
Diversity: 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

20. Sparganium Typha 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.

21. 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

22. Juncaceae
Juncus
Distichia

23. Juncaceae: Juncus
-important in many
wetland habitats

24. 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

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

26. Fig. 7.66D
Fig. 7.65

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

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

29. Cyperaceae

30. 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
-ecologically important, especially in wetlands

31. Cyperaceae: Carex

32. 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

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

34. Ecological
importance

35. Poaceae: vegetative structure
ligule

36. Poaceae: spikelet and flower structure
Images from
Grasses of Iowa

37. 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.

38. Poaceae: caryopsis (grain)
Zea mays
corn or maize
Setaria
foxtail

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

40. 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)

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

42. Dispersal!

43. Poaceae: Bamboos

44. Oryza (rice)

45. Triticum (wheat)

46. Zea (maize or corn)

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

48. 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 obviously
jointed 3
Open
Cymose
6 chaffy tepals
Capsule

49. “Graminoids” - Comparison

50. Next time:
The “Basal” Eudicots…