32 POACEAE. 



spikelet; spikelets ovate-lanceolate, 10-12 cm. long, 5-7-flowered, usually 

 purple; lower glume 5 mm., the upper 7-8 mm. long, acutish; lemmas about 

 7 mm. long, all minutely scabrous. In low meadows, infrequent. 



54. BROMUS. Bromegrass. 



Annuals, biennials or perennials with flat leaves and terminal 

 panicles of large spikelets; peduncles thickened at the summit; 

 spikelets few-many-flowered; glumes unequal, acute; lemmas 

 rounded on the back, or sometimes compressed-keeled, 5-9- 

 nerved, the apex usually 2-toothed, generally bearing an awn 

 just below the summit; palea shorter than the lemma; grain 

 adherent to the palea. 



Spikelets strongly flattened. 



Awns less than 7 mm. long. B. marginalus. 



Awns more than 7 mm. long. B. carinatus. 



Spikelets subterete, not strongly flattened. 



Perennial, native; spikelets narrow, pubescent. B. eximius. 



Annuals or biennials, introduced. 



Awn much longer than the body of the lemma. 



Lemma pubescent; awns 13-15 mm. long. B. lectorum. 



Lemma not pubescent; awns longer. 



Awns 20-30 mm. long. B. sterilis. 



Awns 35-45 mm. long. B. maximus. 



Awn not longer than the body of the lemma, or none. 



Awns minute or wanting. B. brizaeformis. 



Awns well developed. 



Panicle dense, small. B. hordeaceus. 



Panicle loose, open. 



Sheaths glabrous. B. secalinus. 



Sheaths pubescent. B. commutatus. 



Bromus marginatus Nees. Perennial, tufted; the stout stems about 1 m. 

 high; leaf blades coarse, sparsely pubescent; panicle 15-25 cm. long, rather 

 narrow, the branches in whorls of 2-4, about 7 cm. long, and bearing two spike- 

 lets; spikelets 2.5-4 cm. long, 5-7 mm. wide, compressed and keeled, 7-9- 

 flowered; lemma rough-pubescent, 11-14 mm. long, 2-toothed at apex, and 

 bearing a stout awn 4-7 mm. long. Mostly in mountain woods. 



Bromus marginatus latior Shear. Larger and stouter, 100-150 cm. tall; 

 panicle 20-30 cm. long; the lower branches 10-20 cm. long. Common at the 

 edges of wheat fields, roadsides, etc. 



Bromus carinatus Hook. & Arn. Short-lived perennial or sometimes 

 annual; sheaths and blades pilose; glumes glabrous or nearly so; awns of the 

 lemmas 7-10 mm. long; otherwise similar to B. marginatus. In sandy or 

 gravelly soil, especially along Snake River. 



Bromus eximius umbraticus Piper. Perennial; the stem slender, 80-100 

 cm. tall; leaf blades 15-25 cm. long, glabrous or sparsely pilose; sheaths 

 pilose with spreading or reflexed hairs; ligule truncate, fringed, 3-5 mm. long; 

 panicle sparse, more or less nodding, 8-12 cm. long; spikelets 2-3 cm. long, 

 2-4 ram. wide; lemma 8-10 mm. long, sparsely pubescent on the back, some- 

 what ciliate on the margin, the awn 6-9 mm. long. In woods, Thatuna Hills. 



Bromus tectorum L. Annual, 20-60 cm. tall, mostly erect; panicle one- 

 sided, drooping, the slender branches in threes and fours, and bearing several 



