MANUAL OF THE GRASSES OF THE UNITED STATES 33 



Panicle larger, usually erect, the branches more or less drooping. Blades mostly 

 wide and lax. 

 Ligule 3 to 4 mm. long; blades pilose above, scabrous or smooth beneath; 

 panicle large, open, the slender branches long, drooping. 



16. B. PACIFICUS. 

 Ligule short; blades pubescent or pilose on both surfaces, or glabrous or 

 scabrous. 



Blades densely short-pubescent on both surfaces 15. B. grandis. 



Blades more or less pilose or glabrous. 



Sheaths, at least the lower, retorsely pilose (rarely glabrous in B. purgans) 

 blades mostly more than 5 mm. wide. 

 Sheaths shorter than the internodes. Nodes 4 to 6.... 20. B. purgans. 

 Sheaths as long as or longer than the internodes. 



Second glume 5-nerved; nodes 6 to 8; sheaths without flanges at the 



mouth 22. B. nottowayanus. 



Second glume 3-nerved; nodes 10 to 20; sheaths with prominent 



flanges at the mouth 21. B. latiglumis. 



Sheaths glabrous; blades mostly less than 5 mm. wide.... 26. B. frondosus. 



Section 3. Bromium 



Panicle contracted, rather dense, the branches erect or ascending. 



Lemmas glabrous 37. B. racemosus. 



Lemmas pubescent. 



Spikelets compressed; lemmas rather thin and narrow 31. B. molliformis. 



Spikelets turgid; lemmas rather thick, broader 30. B. mollis. 



Panicle open, the branches spreading. 

 Awn short or wanting; lemmas obtuse, inflated (see also short-awned forms of B. secalinus). 



27. B. BRIZAEFORMIS. 



Awn well developed. 



Foliage glabrous 28. B. secalinus. 



Foliage pubescent. 



Branches of the panicle rather stiffly spreading or drooping, not flexuous; awn straight. 



29. B. COMMUTATUS. 



Branches lax or flexuous, usually slender, but rather stout in B. squarrosus. 



Spikelets inflated, 5 to 8 mm. or even 10 mm. wide; awns flattened, strongly 

 divergent, about 1 cm. long; panicle branches stout but flexuous, bearing 



1 or 2 spikelets 33. B. squarrosus. 



Spikelets not inflated, usually less than 5 mm. wide, if more the spikelets pubescent; 

 awn not strongly flattened, straight or somewhat spreading. 

 Panicle 8 to 11 cm. (rarely to 15 cm.) long; branches and pedicels conspicu- 

 ously flexuous or curled; lemmas pubescent 36. B. arenarius. 



Panicle 15 to 25 cm. long (smaller in depauperate specimens), the long branches 

 spreading or drooping, somewhat flexuous but usually not curled; lemmas 

 glabrous or scaberulous. 

 Palea distinctly shorter than its lemma; awn flexuous, usually somewhat 



divergent in drying; spikelets rather turgid 34. B. japonicus. 



Palea about as long as its lemma; awn straight or nearly so in drying; spikelets 

 thinner and flatter, scarcely turgid 35. B. arvensis. 



Section 4. Eubromus 



Panicle contracted, erect; awn 12 to 20 mm. long. 



Culms pubescent below the dense panicle 39. B. rubens. 



Culms glabrous below the scarcely dense panicle.... 40. B. madritensis. 



Panicle open, the branches spreading. 



Second glume usually less than 1 cm. long; pedicels capillary, flexuous. 



41. B. TECTORUM. 

 Second glume more than 1 cm. long; pedicels sometimes flexuous but not capillary. 



Awn about 2 cm. long; first glume 8 mm. long 38. B. sterilis. 



Awn 3 to 5 cm. long; first glume about 15 mm. long 37. B. rigidus. 



Section 5. Neobromus 

 A single species 42. B. trinii. 



Section 1. Ceratochloa (Beauv.) Griseb. 



Annuals, biennials, or perennials; spikelets large, distinctly compressed; 

 glumes and lemmas keeled, rather firm. 



