14 BVLLETIX 772, U. S. DEPARTMENT OF AGRICULTURE. 
Key to the genera of Agrostideae. 
la. Glumes wanting; a low annual 58. Coleanthts. 
lb. Glumes present (the first obsolete in Muhlenbergia schreberi and 
sometimes in Brachyelytrum and Phippsia) 2 
2a. RaeMlla articulate below the glumes, these falling with the 
spikelet 3 
3a. Spikelets in pairs in a spikelike panicle, one perfect, the 
other staminate or neuter, the pair falling together. 63. Lycous. 
3b. Spikelets all alike 4 
4a. Glumes long-awned 62. Polypogox. 
4b. Glumes awnless 5 
5a. Rachilla not prolonged behind the palea ; panicle 
dense and spikelike: glumes united toward the 
base, ciliate on the keel 61. Alopecttbus. 
5b. Rachilla prolonged behind the palea; panicle nar- 
row or open, not dense ; glumes not united, not 
ciliate on the keel 6 
6a. Panicle narrow; lemma with a slender bent 
twisted awn from the bifid apex 60. Limxodea. 
6b. Panicle open and drooping ; lemma with a minute 
straight awn just below the entire apex 59. Cixxa. 
2b. Rachilla articulate above the glumes 7 
7a. Fruit dorsally compressed, indurate, smooth and shining, 
awnless 74. Milium. 
7b. Fruit laterally compressed or terete, awned or awnless 8 
8a. Fruit indurate, terete, awned, the nerves obscure ; callus 
well developed, oblique, bearded 9 
9a. Awn trifid, the lateral divisions sometimes short, 
rarely obsolete (when obsolete no line of demar- 
cation between awn and lemma as in the 
next)' 77. Abistida. 
9b. Awn simple, a line of demarcation between the awn 
and the lemma 10 
10a. Awn persistent, twisted and bent, several to 
many times longer than the slender fruit : callus 
sharp-pointed 76. Sttpa. 
10b. Awn deciduous, not twisted, sometimes bent, 
rarely more than 3 or 4 times as long as the 
plump fruit ; callus short, usually obtuse- 75. Obyzopsis. 
8b. Fruit thin or firm, but scarcely indurate, if firm, the 
nerves prominent or evident ; callus not well devel- 
oped 11 
11a. Glumes longer than the lemma (lemma equaling 
the glumes in Agrostis spica-venti, A. aequivalvis, 
and A. thurberiana) 12 
12a. Panicle feathery, capitate, nearly as broad as 
long; spikelets woolly 66. Lagubus. 
12b. Panicle not feathery; spikelets not woolly 13 
13a. Glumes compressed-carinate, abruptly mu- 
cronate, stiffly ciliate on the keels; 
panicle dense, cylindric or ellipsoid- 64. Phleum. 
13b. Glumes not compressed-carinate, not ciliate 14 
