320 POACE^. 



Fam. 2:495 (1763). Avena Hall, Scop. Introd. 74 (1777). Tricho- 

 (Hum Michx. Fl. Bor. Am. 1:41 (1803). Becandolia Bast. FL 

 Maine-et-Loire, 28 (1809). Agraulus Beauv. Agrost. 5 (1812). 

 Xesonema Rafin. Neogenyt. 4 (1825). Pereilema Presl, Reliq. 

 Hgenk. 1:233, t. 37 (1830). Bromidium Xees, PL Meyen. 154 

 (1835). 



S])ikelets 1-4 mm. long, l-flowered, pedicellate in a loose spread- 

 ing or narrow or even spikelike panicle, the racliilla articulate above 

 the outer glumes, glabrous or nearly so, not produced beyond the 

 flower. The two outer glumes persistent, narrow, keeled, acute, 

 unawned; floral glume shorter, broad, delicately hyaline, unawned 

 or wntli a slender twisted dorsal awn, attached below, or sometimes 

 above the middle; palea very thin, not over half the length of its 

 glume, often very minute or none. Stamens 3. Styles very short, 

 distinct. Grain enclosed but adherent. 



Elegant tufted or creeping annual or perennial grasses, tlie 

 blades flat or setaceous, the panicles terminal, often slender with 

 many filiform branches, spikelets very numerous. 



There are about 100 species, very Avidely distributed in temper- 

 ate and in cold climates; a few are almost cosmopolitan. A small 

 number are prominent for meadows, pastures, and lawns. 



It is very difficult to separate the genus into sections; the pres- 

 ence of a dorsal awn or the absence of an awn has been used, but 

 this has been shown to be a very inconstant and unreliable charac- 

 ter, as some of the seedlings from the same plant have awns on the 

 florets, while others have none. 



A. Floret awned (a) 



a. Awn exserted (d) 



d. Awn very slender, flexuose, over 5 mm. long. . 1, 2 



d. Awn bent, not flexuose, shorter (e) 



e. Panicle thin, branches thin, flexuose. ... 3 



e. Panicle stout, branches ascending 4 



e. Panicle slender, open, small 5, G 



e. Panicle spikelike (p) 



p. Plants dwarf, 4-10 cm. higli 7 



p. Plants much taller 8 



