240 



POACEAE 



1. A. dasystacliynm. 

 2. A. riparium. 



Creeping rhizomes present. 



Glumes and lemmas not awn-pointed. 

 Lemmas pubescent. 



Lemmas glabrous or minutely pubescent. 

 Glumes and usually lenmias awn-pointed. 



Blades thin, flat, usually sparsely pilose above; rhizomes yellowish; lemmas glabrous. 



3. A. repens. 

 Blades firm, not pilose, usually becoming involute, the nerves prominent on the upper surface; rhizomes 

 pale. 

 Spikelets rather distant; spike mostly more than 15 cm. long; lemmas pubescent, rather thin and 



not strongly pointed. 4. A. clmeri. 



Spikelets crowded; spike mostly less than 15 cm. long; lemmas glabrous (pubescent in molle) , 

 firm and strongly pointed or short-awned. 5. A. smithii. 



Creeping rhizomes wanting. 



Lemmas awnless or short-awned. 

 Nodes appressed pubescent. 

 Nodes glabrous. 



Glumes narrow, blunt or abruptly pointed; blades narrow, usually involute. 

 Glumes broad, acute or acuminate; blades flat, mostly 3-6 mm. wide. 

 Spikes slender, the spikelets more loosely arranged, green. 

 Spikes relatively short and thick, the spikelets closely overlapping, usually violet-tinged. 



9. A. violaceum. 

 Lemmas long-awned. 



Awn straight or nearly so; blades flat. 



Spikelets distant, scarcely reaching the one above on the opposite side. 

 Spikelets overlapping. 

 Awn strongly divergent. 



Glumes acute or awn-pointed. 

 Glumes distinctly awned. 



Rachis disarticulating at maturity; glumes slender, 2-nerved. 

 Rachis not disarticulating at maturity; glumes broad, 3-5-nerved. 



6. 



A. parishii. 

 A. inernie. 



8. A. tencnim. 



10. A. laeve. 



11. A. caninttm. 



12. A. spicatnm. 



13. A. saxicola. 



14. A. priiiglei. 



1. Agropyron dasystachyum (Hook.) Vasey. 

 Downy Wheat-grass. Fig. 567. 



Triticum repens dasystachyum Hook. Fl. Bor. Am. 2: 254. 1840. 

 Triticiim repens siibiillosum Hook. Fl. Bor. Am. 2: 254. 1840. 

 Agropyron dasystachyum Vasey, Grasses L'. S. 45. 1883. 

 Agropyron dasvstaclivuni subz'illosum Scribn. & Smith, U. S. Dept. 



Ag"r. Div. Agrostl Bull. 4: 33. 1897. 

 Agropyron lanceolatum Scribn. & Smith, L'. S. Dept. Agr. Div. 



Agrost. Bull. 4: 34. 1897. 

 Agropyron subz-illosum E. Nels. Bot. Gaz. 38: 378. 1904. 



Culms 40-100 cm. tall, from creeping rhizomes; blades 

 narrow, mostly involute, scabrous ; spike erect, 5-12 cm. 

 long; spikelets few-flowered, 1-1.5 cm. long; glumes 

 lanceolate, the first narrow, 3-5-nerved, 8 mm. long, the 

 second broader, S-7-nerved, 9 mm. long ; lemmas 8-10 

 mm. long, villous-pubescent or only scabrous-pubescent, 

 acute or awn-pointed. 



Dry or sandy soil, in the L'pper Sonoran Zone; eastern Wash- 

 ington to northeastern California (Lassen County), east to Colo- 

 rado. June-July. Type locality: on the Saskatchewan. 



2. Agropyron riparium Scribn. & Smith. 



Montana Wheat-grass. 



Fig. 



568. 



Agropvron riparium Scribn. & Smith, L". S. Dept. Agr. Div. 

 Agrost. Bull. 4: 35. 1897. 



Plant pale, often glaucous ; culms erect, 50-100 

 cm. tall, from slender pale rhizomes ; sheaths 

 smooth ; blades flat or involute, rather stiflf, 1-3 

 mm. wide, narrowed to a sharp point, scabrous 

 above, glabrous beneath; spikes slender, 5-15 cm. 

 long; spikelets rather distant, often not reaching 

 the one above on the same side, 10-15 mm. long, 

 glabrous ; glumes 4-7 mm. long, rather abruptly 

 acute ; lemmas acutish or rather obtuse, the lower 

 7-10 mm. long. 



Dry sandy or gravelly soil, in the Transition Zone; east- 

 ern Washington and Oregon to North Dakota, south to Ne- 

 vada and Colorado. July- Aug. Type locality: Montana. 



