POACEAE. 53 



Spikelets compressed, remote on the axis ; awns divergent. 



Spikelets erect. 2 A. Vaseyi. 



Spikelets spreading. 



Empty glumes acute or obtuse ; stem-leaves 3-4, not glaucous. 



3. A. spicatum. 

 Empty glumes acuminate or awn-pointed ; stem-leaves 6-7, glaucous. 



4. A. ariaoiiicuiii. 

 Spikelets subterete, approximate on the rachis or somewhat distant in A. 



tenerum. 

 Awn strongly divergent. 16. A. Bakeri. 



Awn erect or none. 



Awn long, usually longer than the body of the flowering glume. 



Plant tall, over 3 dm. high, erect or ascending ; empty glumes broadest 

 below the middle ; spike elongated. 

 Stem stout; spike 7-10 mm. wide, erect but usually unilateral; 

 spikelets (excluding the awns) 12-15 nim. long. 



5. A. Richardsoni. 

 Stem slender ; spike about 5 mm. wide, usually nodding, seldom uni- 

 lateral ; spikelets (excluding the awns) about i cm. long. 



6. A. caninum. 

 Plant 2-3 dm. high, densely tufted, decumbent at the base, geniculate ; 



empty glumes broadest above the middle ; spike short. 



7. A. andimtm. 

 Awn short or none. 



Spike stout and dense, 3-8 cm. long, usually tinged with purple ; empty 



glumes broadest above the middle. 8. A. violaceum. 



Spike slender and lax, 7-20 cm. long, green ; empty glumes broadest 

 below the middle. 9. A. tenerum. 



Stoloniferous, sometimes slightly tufted ; innovations extra-vaginal ; flowering 

 glumes acute or merely awn-pointed. 

 Sheath not pubescent. 



Flowering glumes glabrous or merely scabrous. 



Spikelets erect, nearly cylindrical or slightly compressed. 



Leafblades hairy above ; empty glumes shorter than the spikelets, 



which are usually distant. 10. A. lanceolatxim. 



Leafblades scabrous but not hairy, spikelets usually not very lax. 

 Empty glumes nearly equalling the spikelets ; spike elongated. 



11. A. pseudorepens. 

 Empty glumes half as long as the spikelet ; spike short. 



12. A. riparium. 

 Spikelets spreading, much flattened. 13. A. occidentale. 



Flowering glumes densely pubescent. 14. A. molle. 



Sheaths pubescent ; flowering glumes very scabrous or short-pubescent. 



15. A. Palmeri. 



1. Agropyron Scribneri Vasey. On high mountain-tops from Mont, to 

 Colo, and Ariz. — Alt. 10,000-13,000 ft. — Silver Plume; Gray's Peak; near 

 Pagosa Peak ; Cumberland Mine, La Plata Mountains ; Mt. Garfield ; Bald 

 Mountain; West Spanish Peak; Buena Vista; headwaters of Clear Creek; 

 Cameron Pass ; mountains above Beaver Creek. 



2. Agropyron Vaseyi S. & S. On dry hills and mountain-sides from Mont. 

 to Ore., Colo, and Utah. — Alt. 5000-6000 ft. — ^Vicinity of Boulder; Ute Pass; 

 Golden; Horsetooth Gulch; gulch west of Soldier Caiion; foot-hills of 

 Larimer Co. 



3. Agropyron spicatum (Pursh) Rydb. {A. diver gens Nees; A. sfrigosmn 

 Coult.) On dry hills and mountains from Mont, to Wash., Ariz, and Calif. 

 — Alt. 5000-6500 ft. — Hot Sulphur Springs, Middle Park; along Platte River; 



