POACEAE. 19 



Spikelets borne in panicles of racemes. 



Glumes more or less compressed and keeled. 



Spikelets cordate, large. 59. BRIZA. 



Spikelets not cordate. 



Plants dioecious ; flowering glume of the pistillate spikelets 

 coriaceous ; palet strongly 2-keeled and serrate on the 

 margin. 60. DISTICHLIS. 



Plants with perfect flowers or in some species of Poa dioe- 

 cious ; spikelets all alike ; flowering glume thin ; palet 

 ciliate or smooth on the margin 

 Flowering glumes scarious-margined ; rachis glabrous or 



with webby hairs. 61. POA. 



Flowering glumes membranous, not scarious-margined ; 

 rachis with stiff hairs, extending into a hairy appendage. 



34. GRAPHEPHORUM. 

 Glumes rounded on the back, at least below. 



Flowering glumes obtuse or acutish and scarious at the apex, 



usually toothed. 

 Flowering glumes distinctly 5~7-nerved ; style present. 



62. PANICULARIA. 

 Flowering glumes obscurely s-nerved ; style none. 



63. PUCCINELLIA. 



Flowering glumes acute, pointed or more commonly awned at 



the apex. 64. FESTUCA. 



Stigmas plainly arising below the apex of the ovary which is tipped 

 by a hairy cushion. 65. BROMUS. 



TRIBE 10. HORDEAE. 



Spikelets usually single at the nodes of the rachis. 



Empty scales broad, with their sides turned towards the rachis. 



66. AGROPYRON. 



Empty glumes with their back turned to the rachis. 70. LOLIUM. 



Spikelets 2-6 at each joint of the rachis, or if solitary the empty glumes arranged 



obliquely to the rachis. 



Spikelets i -flowered or with a rudimentary second flower. 67. HORDEUM. 



Spikelets 2-many-flowered. 



Rachis of the spikes articulated, readily breaking up into joints. 



68. SITANION. 

 Rachis of the spikes continuous, not breaking up into joints. 



69. ELYMUS. 



Tribe i. ANDROPOGONEAE. 

 i. SCHIZACHYRIUM Nees. BUNCH-GRASS, BROOM-GRASS. 



i. Schizachyrium scoparium (Michx.) Nash. (Andopogon scoparium 

 Michx.) On sandy or dry gravelly hills from N. B. to Sask., Fla. and Tex. 

 Alt. 4000-7500 ft. Near Boulder; Cheyenne Mountain; Engelmann Canon; 

 New Windsor, Weld Co.; Royal Gorge; La Porte, Tobe Miller's ranch; 

 Poudre Canon; Ft. Collins. 



2. AMPHILOPHIS Nash. 



i. Amphilophis Torreyanus (Steud.) Nash. (Andropogon saccharoides of 

 Coult. Man.; not Sw.) In dry soil from Mo. to Colo., Tex. and Ariz.; also 

 in Mex . Alt. 4000-5500 ft. Canon City. 



