126 A TEXT-BOOK OF GRASSES 
before (Par. 152). The sterile lemma of Andropogonee, 
also below the perfect floret as in Panicexe, is membrana- 
ceous, thinner than the glumes, often very delicate. In 
the tribe Phalaridez, there are usually 2 sterile florets at 
the base of the terminal fertile floret (Fig. 34). These 
lateral florets may be empty (Phalaris, Anthoxanthum) 
or staminate (Savastana). 
156. The awns are bristle-like continuations of the 
nerves of the glumes or lemmas. Awns involve vascular 
tissue while hairs of various kinds (trichomes) involve 
only epidermal tissue. The commonest position for the 
awn is terminal as in Festuca, where the midnerve is 
extended as a bristle. Often the apex of the lemma is 
cleft and the awn arises from between the lobes or teeth. 
Occasionally the 2 teeth thus formed are also awned. 
Sometimes the lateral nerves of the lemma extend into 
teeth or awns (Tridens). 
In the cases mentioned, the central awn is terminal. 
Sometimes the awn arises below the apex of the lemma 
even nearly at the base, in which case it is said to be dorsal. 
When the awn is dorsal, the lemma shows no midnerve 
above the point of attachment of the awn or rather above 
the point where the midnerve separates from the tissue 
of the lemmas, thus forming an awn (Fig. 45). The awns 
of Aristida (Fig. 35) are usually trifid, with divergent 
often much-elongated branches (as much as 4 inches long 
in a South American species). In Pappophorum the 
lemma is divided at the summit into many awns. In 
other genera the awns are hooked, or bent, or variously 
divided, sometimes smooth, but usually scabrous, some- 
times plumose. In several genera the awn is jointed at 
the base and deciduous, as in Oryzopsis, Nassella, Pipto- 
cheetium. 
