DESCRIPTIONS OF TRIBES AND GENERA. 99 



O O O O O Flowering glumes different from 

 those under O to O O O O • 

 <3 Callus, or prolongation of the 

 rachilla, having a tuft of 

 hairs at least one third as 

 long as the flowering glume. 

 X Spikelets all 55 . 



D Flowering glume and 

 palea thin - membrana- 

 ceous. 



136. Calamagrostis. 

 D □ Flowering glume and 

 palea chartaceous, pan- 

 icle spike-like. 



138. Ammophila. 

 G □ □ Flowering glume and 

 palea chartaceous, pan- 

 icles expanded. 



138a. Calamovilfa. 

 XX Spikelets unisexual. 



137. Cinnagrostis. 

 «tf < Callus naked or with a few 

 very short hairs. 

 X Spikelets in a long, narrow, 

 many-flowered panicle. 



124. Epicampes. 

 XX Panicles pyramidal, oval, 

 or short and spike-like. 

 □ Empty glumes some- 

 what shorter than the 

 flowering glumes, 

 spikelets large. 



130. Arctagrostis. 

 □ □ Empty glumes longer 

 than the flowering 

 glumes. 



§ Without a distinct 

 prolongation of the 

 rachilla beyond the 

 palea. 132. Agrostis. 



