GENUS 62. 



GRASS FAMILY. 



227 



62. BOUTELOUA Lag. Var. Cienc. y Litter. 2 : Part 4, 134. 1805. 



Annual or perennial grasses with flat or convolute leaf-blades and numerous spikelets in 

 one-sided spikes. Spikelets i-2-flowered, arranged in two rows on one side of a flat rachis, 

 the rachilla extended beyond the base of the flowers, bearing 1-3 awns and 1-3 rudimentary 

 scales. Two lower scales empty, acute, keeled; flowering scale broader, 3-toothed, the teeth 

 awn-pointed or awned; palet hyaline, entire or 2-toothed. Stamens 3. Styles distinct. 

 Stigmas plumose. Grain oblong, free. [In honor of Claudius Boutelou, a Spanish botanist.] 



About 30 species, particularly numerous in Mexico and in the southwestern United States. 

 Rachilla bearing the rudimentary scales and awns glabrous ; second scale strongly papillose-hispid 



on the keel. i. B. hirsuta. 



Rachilla bearing the rudimentary scales and awns with a tuft of long hairs at the apex ; second 



scale scabrous and sparingly long-ciliate on the keel. 2. B. oligostachya. 



i. Bouteloua hirsuta Lag. Hairy Mesquite- 

 grass. Fig. 548. 



B. hirsuta Lag. Var. Cienc. y Litter. 2: Part 4, 141. 1805. 



Culms 6'-2o' tall, erect, simple or sometimes spar- 

 ingly branched at the base, smooth and glabrous. 

 Sheaths mostly at the base of the culm, the lower short 

 and crowded, the upper longer ; ligule a ring of short 

 hairs; blades i'-s' long, i" wide or less, erect or 

 ascending, flat, scabrous, sparingly papillose-hirsute 

 near the base, especially on the margins ; spikes 1-4, 

 -2' long, usually erect or ascending, the rachis ex- 

 tending beyond the spikelets into a conspicuous point ; 

 spikelets numerous, zk"-$' long, pectinately arranged; 

 first scale hyaline, shorter than the membranous second 

 one, which is strongly papillose-hirsute on the keel ; 

 third scale pubescent, 3-cleft to the middle, the nerves 

 terminating in awns ; rachilla without a tuft of hairs 

 under the rudimentary scales and awns. 



In dry soil, especially on prairies, Illinois to South Dakota and Mexico ; also in Florida. 

 Bristly Mesquite, Black Grama ; Buffalo-grass. July-Sept. 



2. Bouteloua oligostachya ( Nutt. ) Torr. Grama- 

 grass. Mesquite-grass. Fig. 549. 



Atheropogon oligostachyus Nutt. Gen. i : 78. 1818. 



B. oligostachya Torr.; A. Gray, Man. Ed. 2, 553. 1856. 



Culms 6'-i8' tall, erect, simple, smooth and glabrous. 

 Sheaths shorter than the internodes; ligule a ring of 

 short hairs; blades i'-4' long, i" wide or less, involute, 

 at least at the long slender tip, smooth or scabrous ; 

 spikes 1-3, i '-2' long, often strongly curved, the rachis 

 terminating in a short inconspicuous point ; spikelets 

 numerous, pectinately arranged, about 3" long; first 

 scale hyaline, shorter than the membranous second one, 

 which is scabrous and sometimes long-ciliate on the 

 keel, and sometimes bears a few papillae; third scale 

 pubescent, 3-cleft, the nerves terminating in awns ; 

 rachilla with a tuft of long hairs under the rudimentary 

 scales and awns. 



On prairies, Wisconsin to North Dakota, south to Texas 

 and Mexico. Blue or Common Grama, Buffalo-grass. July- 

 Sept. 



63. ATHEROPOGON Muhl.; Willd. Sp. PL 4: 937. 1806. 



Perennial grasses with narrow flat leaf-blades and an inflorescence composed of numerous 

 short scattered i-sided spreading or reflexed spikes. Spikelets i-flowered, crowded in 2 rows, 

 sessile, imbricated, the rachilla articulated above the empty scales and extending beyond the 

 flower, its summit bearing scales or awns. Scales 3 or more, the lower 2 empty, unequal, 

 acute, narrow, keeled, the third scale thicker and broader, enclosing a narrow 2-toothed 

 hyaline palet and a perfect flower, 3-toothed at the apex, the teeth more or less awned, the 

 small upper scales minute, awned. Stamens 3. Styles distinct. Stigmas plumose. Grain 

 free, enclosed in the scale. [Greek, in reference to the awns of the flowering scales.] 



Species about 15, natives of temperate and tropical regions. Type species: Atheropogon 

 apludoides Muhl. 



