Poaceae (Gramineae)
(Grass Family)
Habit
- Ours annual or perennial herbs (few species large and "woody" such as bamboo);
plants mostly
synoecious (rarely
monoecious (maize and rice) or
dioecious (pampas grass))
Stems
- (called
culms) usually rounded (
terete) with swollen solid
nodes and often hollow
internodes
Leaves
-
alternate, often
2-ranked (in 2 vertical rows),
simple
entire,
sheathing often for most of the
internode length (the sheath edges usually overlap but can be
connate, the top of the
sheath often has a membrane called a
ligule that demarcates the blade from the sheath);
blades are flat, bases that continue around the stem above to sheath are called
auricles
Inflorescence
- a
spikelet (a modified
shoot)--often secondarily aggregated into
spikes,
racemes, or
panicles--consisting of
Flowers
- consist of
Fruit
- a
caryopsis also called a "grain" (like an
achene BUT the seed coat is entirely
adnate
to the
ovary wall not just adnate at
placenta thus new name); rarely can be a
berry (in Bambusa)
Diversity
- 600 genera / over 9000 species
Distribution
- cosmopolitan although more species rich in temperate regions than in tropics; dominant in
grassland and
savannah biomes.....now cultivated on
70% of worlds cultivated lands.
Economics
- most economically important family in the plant kingdom (ie., feeds humans either
directly or indirectly through livestock); shelter, fodder, lawn turf, industrial uses:
EtOH, insulation; potent causer of hayfever
Notes
- Artificial Key to Ten Genera Required for BIO415
Images
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