CHAPTER XXI 
TrispE IX. AVENEA 
A MODERATELY large tribe of about 30 genera, found in 
the cooler parts of the world. Spikelets 2- to several- 
flowered, in open or contracted panicles or sometimes in 
racemes; lemmas usually shorter than the glumes, usually 
awned on the back or from between the teeth of a bifid 
apex, the awn bent and often twisted, the callus and 
usually the rachilla-joints hairy. Only a few of the genera 
are found in America. In all these except Aira, an intro- 
duced genus, there is a prolongation of the rachilla behind 
the uppermost floret; and except in some species of Spheno- 
pholis and in the American species of Koeleria the lemma is 
awned. These genera are usually placed in Festucee, but 
in all characters except the absence of the awn they show 
affinity with the genera of Avenez. 
Key To GENERA OF AVENE 
A. Articulation below the glumes, these deciduous 
with the whole or a part of the spikelet. 
B. Glumes longer than the 2 florets, pubescent.. NoTHOLCUS 
BB. Glumes shorter than the 2 or 3 florets, (Par. 238). 
glabrous or scabrous, the second widened 
Ee a Bia SG SO hd a eel a Sig SPHENOPHOLIS. 
AA. Articulation above the glumes and between 
the florets. 
B. Lemma awnless or mucronate; inflorescence 
a spike-like panicle; an erect perennial.... K@LERIA. 
BB. Lemma awned. 
c. Rachilla not prolonged; spikelets 2-flow- 
ered; delicate introduced annuals....... AIRA. 
ce. ero prolonged behind the uppermost 
oret. 
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