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. marginatus. 



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. tectorum. 



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 mm. 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 



