132 THE TRUE GRASSES. 



spikes ; upper sterile glumes usually tliree-awned. — B. 

 hirsvta Lag., Illinois to Mexico. 



Sec. II. AtJieropogon Muhlenb. (as a genus) (Heteros- 

 tega Desv.). Spikelets few (less than twelve) in many 

 short spikes ; upper sterile glumes variable (see Fig. 70). 

 — B. racemosa Lag., New York to Peru. 



Sec. III. Triathera Desv. (as a genus) (Aristidium 

 Endl., Tricena Kunth). Spikelets either single or in twos 

 or threes in each of the numerous spikes ; upper sterile 

 glume three-awned. — B. aristidoides Griseb., in Mexico, 

 California, etc. 



Sec. IV. Polyodon Kunth (as a genus) Triplathera 

 Endl.). Like Sec. Ill, but with 2-3 sterile bracts above 

 the £ flower ; sterile bract with 3-5 awns united in a 

 fascicle. — B. multiseta Benth. in S. America. — B. Texana 

 Wats, in Texas. 



182. (182) Melanocenchris Nees (Ptiloneilema Steud.). 

 Spikes very short, sub-globose, very remote, finally de- 

 ciduous. Low annuals. 



Species three, in Hindostan and tropical Africa. 



183. (183) Tripogon Koth. (Plagiolytrum Nees). Spikes 

 terminal, elongated, solitary ; spikelets sub-imbricated, 

 many-flowered, the 1-2 upper flowers smaller, i , or 

 sterile. Small, c«spitose grasses with very narrow 

 leaves. 



Species eight, in East India and tropical Africa. 



18-4. (184) Lepidopironia Richard. May belong to the 

 preceding ; it differs only in the uni-aristate flowering- 

 glume, which is covered with long woolly hairs. 



Species one, in Abyssinia. 



185. (185) Tetrapogon Desf. (CryptocMoris Benth.). 

 Spikes solitary or in twos or threes, usually clothed with 

 silky hairs ; spikelets crowded, 2-3-flowered, broad. 



Species five, four in North Africa, Abyssinia, and 

 Western Asia. One (CryptocMoris) of doubtful origin (in 

 Patagonia?). 



186. (186) Astrebla F. Midi. Spikes terminal, soli- 

 tary or in pairs ; spikelets large, thickened ; empty glumes 

 and flowering glumes many-nerved, the latter clothed 

 with silky hairs. 



