64 POACEAE 



1. S. pectinata Bosc. Stem 1-2 m. high, glabrous, stout; leaf -blades 3-6 

 dm. long, 6-15 mm. wide, scabrous on the margin, usually flat, becoming in- 

 volute; spikes 5-30, often short-peduncled, 5-12 cm. long; rachis rough on the 

 margins; spikelets 12-14 mm. long; first empty glume equalling the lemma. 

 S. cynosuroides A. Gray, not Willd. S. Michauxiana Hitchc. In swamps and 

 streams: N.S.NJ. Tex. Colo. Ore. Mack. Plain Submont. Au-O. 



2. S. gracilis Trin. Stem 3-10 dm. high, glabrous; leaf-blades 2-4 dm. 

 long, 2-6 mm. wide, flat or involute; spikes 4-8, apprised, usually short-stalked, 

 3-5 cm. long; spikelets 6-8 mm. long; first glume half as long as the second and 

 the lemma. Saline soil: B.C. Calif. Ariz. Kans. Sask. Plain Submont. 

 Au-S. 



40. BECKMANNIA Host. SLOUGH GRASS. 



Tall grasses with flat leaf-blades. Spikelets 1-2-flowered, orbicular, com- 

 pressed, in two rows on several erect spikes. Empty glumes 2, membranous, 

 saccate, obtuse or abruptly acute. Lemma narrow, thin-membranous. Palet 

 hyaline, 2-keeled. Styles distinct; stigmas plumose. Grain oblong, free. 



1. B. erucaeformis (L.) Host. Stem 4-10 dm. high, glabrous, simple; 

 leaf -blades 7-20 cm. long, 4-8 mm. wide, scabrous; panicle simple or compound; 

 spikes 1-2 cm. long; spikelets 2-3 mm. long, 1-2-flowered; empty glumes sac- 

 cate, abruptly acute; lemma acute or awn-pointed. Wet ground: Yukon 

 Calif. N.M. la. Ont, Plain Mont. Jl-S. 



41. SCHEDONNARDUS Steud. 



Annuals, with involute, subulate leaf-blades. Spikelets 1-flowered, acum- 

 inate, sessile, alternate on opposite sides of the long rachis, forming several long, 

 slender spikes. Empty glumes 2, persistent, narrow, acuminate, somewhat 

 unequal. Lemma longer, rigid, enclosing the narrow shorter palet. Styles 

 distinct; stigmas plumose. 



1. S. paniculatus (Nutt.) Trelease. Annual; branched at the base; stems 

 2-5 dm. high, scabrous; leaf -blades 2-5 cm. long, 1-2 mm. wide, flat, stiff; spike- 

 lets nearly 3 mm. long, sessile and appressed; empty glumes hispid on thejveel, 

 the second much longer than the first and nearly equalling the lemma. S. tex- 

 anus Steud. Sandy soil, especially river banks. Man. 111. Tex. N.M. 

 Sask. Plain Submont. Jl-S. 



42. CHLORIS Sw. 



Usually perennials. Spikelets 1-flowered, often sessile, with 1 or more empty 

 usually awned glumes above the perfect flower, crowded in 2 rows, in verticillate 

 or approximate spikes, the rachilla prolonged beyond the flower. Empty glumes 

 2, persistent, unequal, keeled, narrow, acute or acuminate, awnless or awn- 

 pointed. Lemma acute, usually long-awned, rarely nearly awnless. Palet 

 folded, 2-keeled. Styles distinct; stigmas plumose. 



1. C. brevispica Nash. Perennial; stem 1-3 dm. high; leaf-blades 1-6 cm. 

 long, 1-3 mm. wide, scabrous above and on the margins; spikes 6-10, finally 

 spreading, 2.5-4.5 cm. long; spikelets (exclusive of the awns) about 2.8 mm. long; 

 empty glumes lanceolate, acute; lemma 2.5 mm. long; awn about 2 mm. long; 

 the fourth glume (second lemma) empty, about 1.5 mm. long, with an awn of 

 about the same length. Sandy soil: Tex. e Colo. N.M. Son. Jl-Au. 



43. BOUTELOUA Lag. GRAMA, GRAMA GRASS, MESQUITE GRASS, 

 BUFFALO GRASS 



Perennials or annuals, mostly tufted. Spikelets few or numerous, 1- or 2- 

 flowered, crowded in 2 rows and forming few to man}' one-sided, more or less 

 curved sessile spikes; rachis usually conspicuously prolonged beyond the spike- 

 lets. Lower flowers perfect; the upper when present staminate. Empty glumes 

 2, narrow, acute, unequal, keeled. Lemma usually thinner and broader, 3- 

 nerved, the nerves excurrent. Lemma of the upper -1-3 imperfect flowers borne 

 at the end of a rachilla, 3-awned. Styles distinct; stigmas plumose. 



