20 POACEAE. 



3. ANDROPOGON L. Beard-grass, Blue-stem. 



Fourth glume of the sessile spikelet with a long geniculate awn, more or less 

 spiral at the base. 

 Outer two glumes of the sessile spikelet more or less hispidulous all over ; hairs 



on the rachis-internodes usually 2 mm. or less long. i. A. furcatus. 



Outer two glumes of the sessile spikelet smooth or nearly so, except on the 

 nerves : hairs of the rachis-internodes 3-4 mm. long. 2. A. chrysocomus. 



Fourth glume of the sessile spikelet awnless or with a short, straight, untwisted 

 awn. 3. A. Hallii. 



1. Andropogon furcatus Muhl. In meadows from Me. to Sask., Fla. and 

 Tex. — Alt. 4000-8000 ft. — Near Boulder; La Veta; Golden; West Dry Creek, 

 Larimer Co.; Manitou ; Colorado Springs; Tobe Miller's ranch, near La 

 Porte; Ft. Collins. 



2. Andropogon chrysocomus Nash. Tn dry meadows from Neb. to Colo., 

 Kans. and Tex. — Alt. 4000-8000 ft. — La Veta ; on the plains. 



3. Andropogon Hallii Hack. In sandy soil from Neb. to Mont., Kans. and 

 Mex. — Exact locality not given. 



4. SORGHASTRUM Nash. Indian Grass. 



I. Sorghastrum nutans (L.) Nash. {Chrysopogon nutans Benth.) In dry 

 soil from Ont. to Man., Fla. and Ariz. — Alt. 4000-6000 ft. — Near Boulder; 

 New Windsor, Weld Co.; Cafion City; Tobe Miller's ranch, near La Porte; 

 Ft. Collins. 



5. SORGHUM Pers. Johnson Grass, Sugar Corn. 



I. Sorghum halapense (L.) Pers. Cultivated for fodder and occasionally 

 escaped. — Rocky Ford. 



Tribe 2. ZOYSIEAE. 



6. HILARIA H. B. K. Mesquite, Black Grama. 



Outer glumes of the spikelets cuneate, awnless ; the nerves strongly diverging. 



I. H. mutica. 

 Outer glumes linear or oblong, awned ; the nerves parallel. 2. H. Jamesii. 



1. Hilaria mutica (Buckl.) Benth. On dry plains from southern Colo, to 

 Tex. and Ariz. — Reported from Colorado, but doubtful. 



2. Hilaria Jamesii (Toi'^.) Benth. Hillsides and gulches of the mesas from 

 Wyo. to Nev., Tex. and N. Mex. — Alt. 4000-6000 ft. — Deer Run; mesas near 

 Pueblo; Arboles; Mancos; Hotchkiss, Delta Co. 



Tribe 3. PANICEAE. 



7. SYNTHERISMA Walt. Crab-grass. 



Pedicels terete or nearly so, sparingly if at all hispidulous ; lower sheath glabrous. 



1. S. humifusum. 

 Pedicels sharply 3-angled ; the angles strongly hispidulous ; as are also the sheaths. 



2. S. sanguinale. 



