48 



Agropyron riparium S. & S. (Bank Wheat-grass).— Stems slender, erect, 2 to 3 

 feet high; leaves sparse, mostly basal; spike narrow, spikelets rather distant, 

 giving an interrupted appearance. Occurring both on the saline soil of the 

 plains and the alluvial soil of mountain parks. In the latter situations it often 

 forms meadow-like tracts, indicating that under cultivation it may prove a val- 

 uable member of this imi)ortant genus of grasses. Little Laramie Kiver, July 

 24 (3447); Colorado-Wyoming line, July 22 (3813). 

 Agropyron spicatum S. & S. (Western Wheat-grass). — An erect, rather coarse 

 species with large heads of conspicuous spikelets. It grows as a continuous but 



open sod and yields a large 

 amount of valuable forage. 

 Pine Blulis, July 6 (3610); 

 Evauston, July 27 (3847); 

 Granger, July 30 (3878); 

 Grand Encampment, Au- 

 gust 13 (3997). 

 Agropyrou spicatum molle S. 

 & S. — Very similar to the 

 preceding but smaller; con- 

 fined in this range almost 

 wholly to saline regions, 

 where it is of much impor- 

 tance. Sheep Mountain, 

 July 3 (3299). 

 Agropyron tenerum Vasey 

 (Slender Wheat-grass). — 

 Leaves numerous, stems 

 slender and erect; spikes 3 

 to 6 inches long, the few 

 flowered spikelets closely 

 appressed, awns very short. 

 As previously stated, this 

 seems to be the most valu- 

 able of the wheat-grasses for 

 this range. Pine Bluffs, 

 July 6 (3628); North Ver- 

 milion Creek, July 19 (3773) ; 

 Evauston, July 27 (3846); 

 Granger, July 30 (3880); 

 Grand Encampmeiit, Au- 

 gust 13(3976) ; Medicine Bow 

 River, August 20 (407t)). 

 Agropyron tenenini ciliatum 

 S. «fc S. -^Smaller, more slen- 

 der, spikelets less crowded. 

 A valuable grass, but not 

 widely distributed. North Vermilion Creek, July 18 (37.5.")). 

 Agropyron vaseyi S. A 8. (Vaskv's Whkat-ghass). — In habit and general appear- 

 ance much resimbling ./. divcri/eus. Uke tliat, it occupies dry slopes and the 

 summits of hills, this especially in the "red formations" of the desert. Pine 

 Mountain, head of Vermilion Creek, .Inly 20 ('^797). 

 Agropyron violaceum Vasey fMorxTAix Wiikat-(;rass). — Stems, stout, short, 10 

 to IS inches high, spikes slender, purplish. A grass of much value and wide 

 distribution, iu this range rather rare and confined to the hill country. Laramie 

 Kills, .Inly 17 (3403). 



-Tr~ 



Fio. 21. — Elymus simplex: a, empty gbinies; ?), florets. 



