GRASS FAMILY 65 



Spikes 1-4, rarely more; spikelets 25 oi more. _ 



Spikes usually more than one. 



Awns manifestly arising from between the lobes of tlie lemma; annual. 



1. B. polystachya. 

 Awns terminating the lobes of the lemma; cespitose tufted perennials. 



Stem densely villous below. 2. B. eriopoda. 



Stem glabrous. 



Rachilla bearing the rudimentary glumes and awns glabrous ; second glume 



strongly papillose-hispid on the keel. 3. B. hirsuta. 



Rachilla bearing the rudimentary glumes and awns with a tuft of long 

 hairs at the apex; second glume scabrous and sparingly long-ciliate on 

 the keel. 4. B. gracilis. 



Spike solitary; tufted annual. 5. B. procumbens. 



Spikes 12 or more; spikelets in each few, less than 12. 6. B .curtipendula. 



1. B. polystachya (Benth.) Torr. Cespitose annual; stem geniculate, 

 ascending, 1-3 dm. high; leaf-blades 1-5 cm. long, 1-2 mm. wide, flat, scabrous, 

 ciliate with a few hairs; spikes 4-8, about 2 cm. long; spikelets 1.5-2.5 mm. long; 

 first glume very small, the second shorter than the lemma, purplish; awns not 

 more than half as long as the glumes. Six-week Gr.\ma. River valleys and 

 sandy soil: Tex. — Colo. — Utah — -Calif.; Mex. Son. 



2. B. eriopoda Torr. Stems 3-6 dm. high, densely villous at least below; 

 sheaths glabrous; leaf-blades 5-15 cm. long, 1-2 mm. wide; spikes 2-5, erect on 

 short woolly pedicels, 2-5 cm. long; spikelets 2-flowered, 6-8 mm. long exclusive 

 of the awns; emptv glumes glabrous. Black Grama. Drv soil: Tex.— Colo. — • 

 Utah— Calif.; Mex. Je-0. 



3. B. hirsuta Lag. Stem 1-5 dm. high, glabrous; leaf-blades 2-12 cm. long, 

 2 mm. wide or less, flat, rough, sparingly papillose-hirsute near the base; spikes 

 1-4, 1-5 cm. long, the rachis conspicuously prolonged beyond the spikelets; 

 spikelets numerous, 5-6 mm. long; lemma 3-cleft to near the middle. Hairy 

 Grama. Dry or sandy soil: Minn.— 111.— Tex.— Ariz.— S.D.; Fla.; Mex. 

 Plain — S^lbmont. Je-Au. 



4. B. gracilis (H.B.K.) Lag. Stem 1.5-4 dm. high, smooth and glabrous; 

 leaf-blades 3-10 cm. long, 2 mm. wide or less, flat or when dry involute, usually 

 glabrous; spikes 1-3, often strongly curved, 2-5 cm. long; spikelets numerous, 

 about 6 mm. long; first glume about half as long as the second. B. oligostachya 

 (Nutt.) Torr. Blue Grama. Plains and prairies: Man.— -Wise. — Miss. — ■ 

 Ariz. — Alta.; Mex. Plain — Suhmonl. 



5. B. procumbens (Durand) Griffiths. Stems prostrate or ascending, 1-3 

 dm. high; leaf-blades 2-5 cm. long; spikes solitary, 1-3 cm. long; spikelets 4-5 

 mm. long; first empty glume half as long as the second one; lemma pubescent 

 on the veins, 3-lobed, the middle lobe 2-toothed; middle awn equalling the 

 glumes and twice as long as the lateral ones. B. 'prostrala Lag. Six-week 

 Grama. Sandy plains: Tex. — Colo. — Ariz.; Mex. Son.-Submont. Jl-D. 



6. B. curtipendula (Michx.) Torr. Perennial, with more or less cespitose 

 rootstocks; stem 3-lU dm. high, smooth and glabrous; leaves 5-15 cm. long, 2-4 

 mm. wide, scabrous above; spikes many, 6-15 mm. long, spreading or reflexed; 

 spikelets 4-12, divergent, 7-10 mm. long; emptj- glumes scabrous especially on 

 the keel; lemma 3-toothed at the apex. B. racemosa Lag. Atheropogon curti- 

 pendulum Fourn. Tall Grama. Dry soil: Ont. — N.J. — Tex. — -Ariz. — Sask.; 

 Mex. Plain — Subinont. Jl-S. 



44. LEPTOCHLOA Beauv. 



Annuals or perennials. Spikelets small, usually close, 2-several-flowered, 

 rarely l-flowered, flattened, sessile, in two rows, forming many long slender 

 spikes. Empty glumes 2, keeled, a little unequal, usually shorter than the 

 spikelets. Stj-les distinct; stigmas plumose. 



1. L. filiformis (Lam.) Beauv. Annual, branched at the base; stems 3-10 

 dm. high, erect, glabrous; leaf-blades 5-20 cm. long, 2-6 mm. wide, scabrous; 

 panicle 1-4 dm. long; sjiikes numerous, slender, ascending or spreading, the lower 

 5-15 cm. long; spikelets usually 3-flowered, 2 mm. long; lemma 2-toothed at 

 the apex, ciliate on the nerves. L. ynucrotiala (Michx.) Kunth. Drv soil: 

 Fla.— Va.— 111.— N.M.— Calif.; Mex., W. Ind. Son. Jl-S. 



