The Monocots: Part 2
Commelinid Monocots
Spring 2014
Phylogeny of Monocot Groups
Basal
“Petaloid”
Commelinid
Acorales
Alismatales
Asparagales
Liliales
Dioscoreales
Pandanales
Arecales
Poales
Commelinales
Zingiberales
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 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
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
Arecaceae
Economic plants and products:
Cocos nucifera
Coconut, oil
Arecaceae
Economic plants and products:
Phoenix dactylifera
Dates
Phylogeny of Monocot Groups
Basal
“Petaloid”
Commelinid
Acorales
Alismatales
Asparagales
Liliales
Dioscoreales
Pandanales
Arecales
Poales
Commelinales
Zingiberales
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
Zingiberales
diversity
Fig. 7.56
Phylogeny of Monocot Groups
Basal
“Petaloid”
Commelinid
Acorales
Alismatales
Asparagales
Liliales
Dioscoreales
Pandanales
Arecales
Poales
Commelinales
Zingiberales
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
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:
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 many
wetland 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. 7.66D
Fig. 7.65
Flowers:
•Arranged in spikelets
•Reduced
•Wind-pollinated
•Subtended by one bract
•Reduced/absent perianth
Sedge spikelet
flower +
subtending
bract = floret
Cyperaceae
flower
From Zomlefer 1994
Cyperaceae
Fruit type is the achene: very important in
the taxonomy of the family.
Cyperus
Eleocharis
Rhynchospora
(note bristle perianth)
Cyperaceae
http://waynesword.palomar.edu/termfl3.htm
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
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
Ecological
importance
bamboo
sugar cane
weeds
Economic
importance
Zea mays
Oryza sativa
Triticum aestivum
Poaceae:
vegetative
structure
ligule
Poaceae: spikelet and flower structure
flower
Images from
Grasses of Iowa
(mostly)
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.
Poaceae: caryopsis (grain)
Zea mays
corn or maize
Setaria
foxtail
early grasses
Origin of
grasses
ca. 70-80 mya
in southernhemisphere
forests
Anomochlooideae
Pharoideae
Puelioideae
Origin of
grasses
ca. 70-80 mya
in forests
Bamboos
(Bambusoideae)
Bluegrasses
(Pooideae)
Rices
(Ehrhartoideae)
Panicgrasses*
Major radiation
in OligoceneMiocene epochs
into open habitats
+
(Panicoideae)
Needlegrasses*
(Aristidoideae)
Lovegrasses*
(Chloridoideae)
Micrairoideae*
Stamens
reduced to 3
Reeds
(Arundinoideae)
Oatgrasses
(Danthonioideae)
C4 photosynthetic pathway
(in warm season grasses)
is advantageous under
higher temperatures, higher
light, and less water when
atmospheric CO2 is < 500 ppm
Dispersal!
Poaceae: Bamboos
Oryza (rice)
Triticum (wheat)
Zea (maize or corn)
For more information
and images:
http://www.eeob.iastate.edu/research/iowagrasses/
The Grasses of Iowa
Grasses,
Sedge,
Rushes!
•Triangular,
solid, not
obviously
jointed
•3
•Terete, solid,
not obviously
jointed
•Leaf sheath Open,
ligule
•Closed
•Open
•Inflor: Spikelets
•Spikelets
•Cymose
•Perianth: Lodicules
•None or
bristles/scales
Achene
•6 chaffy tepals
•Stem terete, hollow,
or solid, jointed
•Leaf ranks 2
•Fruit: Caryopsis
•3
•Capsule
“Graminoids” - Comparison
Next time: The “Basal” Eudicots…