sible to separate the sheath from the stem without tearing the 
sheath. In some grasses, the sheath is open — the margins do not 
come together; in others, it is closed — the margins overlap. Some 
sheaths are flattened ; others are rounded. Because of their differ- 
ent forms and shapes, they are important in identifying a grass. 
The ligule, meaning little tongue, usually clasps the stem firmly 
on the inside of the leaf at the junction of the sheath and blade, 
preventing dirt and water from getting between them. In the ab- 
sence of a seedhead, the ligule is often used to identify a grass. 
Some ligules are membranous or papery; some are only a ring 
of hair. 
The collar is on the outside of the leaf at the junction of sheath 
and blade. 
Some grasses have two earlike lobes or appendages, called auri- 
cles, which are borne, one on either side, at the base of the blade. 
Seedhead 
The seedhead (inflorescence) is the flowering (reproductive) 
part of the grass plant. Generally, the seedhead has no leaves. On 
some grasses, a sheathlike bract, called spathe, encloses or partly 
encloses the seedhead. 
The spikelet is the basic unit of the seedhead. It may be pedi- 
celed (on a pedicel or footstalk) or sessile (without a pedicel). 
The spikelet consists of a rachilla (jointed stem or axis), one to 
several florets, and two glumes. The florets are borne in two 
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