744 GRAMINEiE avena 



TRI8ETUM 



smooth except the ring of stiff white hairs at the base, and the scabrous 

 apex. In cultivated fields and waste places : naturalized from Europe. 



A. Smithii Porter, Gray Man. ed. 3, 640. Stems 2-5 feet high, erect, 

 simple, scabrous : sheaths shorter than the internodes, very rough : ligules 

 2 lines long: leaves 4-8 inches long, 3-6 lines wide, scabrous: panicle 6-12 

 inches long, the branches finally spreading: spikelets 3-6-flowered : empty 

 glumes smooth, the second 3-4 lines long, 3-nerved : flowering glumes 5 

 lines long, naked at base, strongly nerved, scabrous, bearing an awn 3^-)^ 

 their length. Eastern Washington to Michigan. 



28 TRISETUM Pers. Syn. i, 97. (1805.) 



Mostly perennial tufted grasses with flat leaves and spike-like 

 or open panicles. Spikelets 2-4-flowered, the flowers all perfect 

 or the uppermost staminate. Rachella glabrous or pilose, exten- 

 ded beyond the flowers. Glumes 4-6, membranous, the two 

 lower empty, unequal, acute, persistent. Flowering glume usu- 

 ally shorter than the empty ones, deciduous, 2-toothed, bearing 

 a dorsal awn below the apex, or the lower one sometimes awn- 

 less. Palet narrow, hyaline, 2-toothed. Stamens 3. Styles dis- 

 tinct. Stigmas plumose. Grain free, enclosed in the glume. 



T. barbatum Steud. Syn. PI. Gram. 229. Stems erect, or decumbent 

 at base, often branched below, smooth, leafy nearly to the panicle, 1-3 feet 

 high: sheaths sparsely retrorsely hispid, half open above, shorter than 

 the internodes: ligules obtuse, erose, 1 line or less long: leaves 3-6 inches 

 long, 2-3 lines wide, scabrous, sparsely pubescent or nearly smooth: pani- 

 cle open to constricted, 4-8 inches long, its branches 3 inches long or less : 

 spikelets loosely 3-6-flowered, 7-10 lines long; first empty glume very nar- 

 rowly ovate, subulate-acute, smooth except the slightly hispid prominent 

 keel, 3-4 lines long; second one lanceolate, acute, 5-6 lines long: flowering 

 glumes lanceolate, with 2 teeth about )^ line long, pubescent, 5-7 lines 

 long : awn inserted at the base of the sinus bent, hispid and twisted below : 

 palet linear thin. Washington to California. 



T. canescens Buckley Proc. Acad. Phil. 1862, 100. Stems erect, 

 nearly smooth, 2-3 feet high : sheaths open above, canescent to nearly 

 smooth, shorter than the internodes : ligules ovate, erose or lacerate, 2-3 

 lines long: leaves flat, 4-10 inches long, 3-4 lines wide, canesfcent to nearly 

 smooth : panicle narrow, 6-8 inches long, its branches unequal, 2 inches 

 or less long, erect: spikelets slightly compressed, 3-4 lines long. 2-flowered 

 or with only 1 imperfect one: first empty glume narrowly ovate, acute, 

 slightly carinate, thin, hispid on the keel , 13^-2 lines long ; second one 

 broadly lanceolate, acute, about 3 lines long : flowering glume ovate-lanceo- 

 late, cleft % wa y from the apex, minutely scabrous, 3 lines long: awn 

 attached at the base of the cleft, hispid, twisted and bent. Common in 

 wooded districts, California to Alaska. 



T. cenmum Trin. Mem. Acad. St. Petersb. 1830, i, 61. Stems slen- 

 der, erect, smooth, 2-3 feet high: sheaths loose, open above, smooth or 

 scabrous above, shorter than the internodes: ligules ovate, lacerate: 1-6 

 lines long: leavea flat, scabrous on both sides or nearly smooth beneath, 

 5-10 inches long, 3-6 lines wide : panicle rather loose, nodding, 5-8 inches 

 long, its branches slender, ascending : spikelets 2-4-flowered, 3-4 lines long : 

 first empty glume narrowly ovate, carinate 1-1K lines long; second one 

 broadly oblong, obtuse or acuminate, thin, hispid on the keel above, 

 3-nerved below, 2-2}4 lines long : awn arising below the base, of the cleft, 

 3-5 lines long. Along streams in the mountains, California to Alaska. 



T. subspicatum Beauv. Agrost. 180. Softly pubescent to glabrous: 



