ANDROPOGONE^ 165 



B. First glume flattened or somewhat convex. 



Florida Manisuris. 



BB. First glume hard and globular, pitted. 



Florida to Arizona Rytilix. 



A.. Axis of the spike or raceme hairy, not exca^ 

 vated nor greatly thickened; fertile lemma 

 usually awned. 

 B. Spikeiets all ahke. 



c. Axis of racemes continuous. 



D. Racemes in a narrow spike-hke panicle; 



spikeiets awnless. Florida Imperata. 



DD. Racemes in a broad fan-shaped panicle; 



spikeiets awned Miscanthus 



cc. Axis of racemes breaking up into joints; (Par. 204). 

 racemes in a much-branched panicle on 

 a main axis. 



D. Spikeiets awned Erianthus 



(Par. 206). 



DD. Spikeiets awnless Saccharum 



BB. Spikeiets not all alike, one of the pair perfect, (Par. 205). 



the other staminate, neutral or reduced to 

 a pedicel. 

 c. Fertile spikelet pedicelled, with a long 

 plumose awn; sterile spikelet nearly 



sessile, awnless Trachypogon. 



cc. Fertile spikelet sessile; sterile spikelet 

 pedicelled; axis articulate. 

 D. Spikeiets awnless; raceme sohtary, ter- 

 minating the culm Elionurus. 



DD. Spikeiets awned; racemes 1 or more 

 from each sheathing bract but not 

 solitary on the culms; sometimes re- 

 duced to the terminal joint of 3 spike- 

 lets and borne in panicles. 

 E. Sessile spikeiets all ahke in the same 

 raceme. 



F. Racemes several-flowered Andropogon 



FF. Racemes reduced to 1 or 2 joints, (Par. 208). 



these in panicles. 



G Awn several inches long Chrysopogon. 



GG. Awn short. 



H. Plants perennial, without rhi- 

 zomes; sterile spikelet re- 

 duced to a pedicel Sorghastrum. 



HH. Plants perennial, with rhi- 

 zomes, or annual; sterile 



spikeiets staminate Holcus 



EE. Sessile spikeiets at the base of the (Par. 210). 



spike different from the others. 



