GRAMINEAE (GRASS FAMILY) 81 



ing rootstocks, often tufted, 3-9 dm. high with prominently striate-nerved 

 sheath and leaves, and strict spikes : leaves rough on both surfaces, acuminate, 

 12-25 cm. long, 2-7 mm. wide: spikes 8-20 cm. long: spikelets 5-10 mm. 

 distant, the lower ones often 2-4 cm. distant, a little compressed, 3-7-flowered: 

 glumes equaling or one third shorter than the spikelet, linear-lanceolate, 

 acuminate or awn-pointed, scarious on the margins, strongly 5-7-nerved, the 

 nerves scabrous or hispidulous, 8-12 mm. long; lemma acuminate or tipped 

 with a weak short aristate awn 1-3 mm. long, smooth and shining on the 

 back below, 5-nerved and usually scabrous above. River bottoms; through- 

 out our range. 



8a. Agropyron pseudorepens magnum Scribn. & Smith, 1. c. Robust, 

 9-12 dm. high, the leaves and spikes longer than in the species: spikelets 

 crowded, 24 mm. long. Colorado and Idaho. 



9. Agropyron occidentale Scribn. U. S. Dept. Agr. Div. Agrost. Cir. 27: 9. 

 1900. A rigid upright, glaucous perennial 3-12 dm. high, from creeping root- 

 stocks, with strongly striate-nerved sheaths, culms, and leaf-blades: leaves 

 rigid, smooth or slightly scabrous on the back, rough-scabrous on the margins 

 and along the prominent nerves above, becoming involute, 10-18 cm. long, 

 4-6 mm. wide; those of the innovations narrower and often half as long as the 

 culms: spikes straight, beardless, 6-14 cm. long: spikelets compressed, spread- 

 ing, 6-10 mm. distant, 7-13-flowered, 12-20 mm. long: glumes one half to 

 two thirds as long as the spikelets, rigid, narrowly lanceolate-acuminate, 

 usually tipped with an awn less than 3 mm. long, 3-nerved, the mid-nerve 

 usually strong and prominent, scarious on the margins at the middle and 

 below, scabrous on the nerves, 7-18 mm. long; lemma smooth or granulose- 

 roughened on the back, acute or acuminate, mucronate or tipped with an awn 

 2-3 mm. long. Plains, bench lands and river bottoms; throughout our range. 



9a. Agropyron occidentale molle Scribn. 1. c. Rachis, glumes, and lemma 

 more or less villous-pubescent. Throughout our range. 



10. Agropyron dasystachyum (Hook.) Scribn. Hull. Torr. Hot. Club 10: 78. 



Hat her stout, glaucous, from running rootstocks, smooth or finely 

 pubescent or scabrous on the lower sheaths and on the leaf-blades above, 

 4-9 dm. high: leaves flat or becoming involute, 5- -25 cm. long, 2-6 mm. wide; 

 those of the innovations narrower and longer: spikes 7-17 cm. long: spikelets 

 subcompressed or nearly cylindrical, 8-10 mm. distant, 4-8-flowered, 16-20 

 mm. long: glumes half or less than half as long as the spikelets, narrowly 

 lanceolate or oblanceolate, acuminate or short-awned, 3 -5-iu-rvcd, with rather 

 prominent scarious white margins, villovs-pubescent, 6-10 mm. long; lemma 

 acute, awnless, mucronate or short-awned, rarely bidentate, 5-nerved toward 

 the apex, villous. Sand hills and dunes; Hudson Hay to \\ 'yoming and Idaho. 



11. Agropyron subvillosum (Hook.) E. Xels. Hot. Ciaz. 38: 378. 1904. A 

 light green or somewhat glaucous perennial with running rootstocks, smooth 

 or finely pubescent on the lower sheaths and the leaf-blades above, the culms 

 slender, 2-7 dm. high: leaves narrow, becoming 4-lS cm. long, 1-3 mm. wide: 

 spikes 5-16 cm. long: spikelets compressed or nearly cylindrical, 4-11 mm. 

 distant, 3-7-flowered, 10-16 mm. long: glumes one third to one half as long 

 as the spikelets, lanceolate, acuminate or cuspidate-acuminate, 3-nerved, 

 scarious on the margins, scabrous or pubescent or nearly smooth, 4-7 mm. 

 long; lemma relatively broad, acute, truncate, mucronate or bidentate, 3-5- 

 nerved toward the apex, sparsely villous, scabrous or nearly smooth on the 

 back. Plains and bench lands; throughout our range, extending northward 

 and westward. 



63. HORDEUM L. BARLEY 



Coarse erect grasses with numerous flat leaves. Spikelets 5-10-flowered, per- 

 fect, compressed with the edge to the axis, sessile and alternately 2-ranked in 

 long rigid terminal spikes. Upper glume external, rigid, 5-7-nerved; lower 

 glume wanting except in the terminal spikelets; lemma coriaceous, 3-5-nerved, 

 obtuse or subacute, short-awned or awnless, convex, smooth, nearly equaled 

 by the palet and large adherent grain. 



ROCKY MT. EOT. 6 



