MACLOSKIE I GRAMINE^E. 2 I I 



36. BOUTELOUA Lag. 



Spikes i -sided, ultimately drooping. Spikelets in 2 rows on the rachis, 

 i-2-flo\vered, the rachilla prolonged, bearing bristles or rudimentary 

 flowers. The 2 lower empty glumes acute, keeled ; the floral glume 3- 

 toothed ; palea narrow, entire or 2-toothed ; stamens reddish. Upper 

 empty glumes 3~5~awned or divided. Grain oblong, enclosed but free. 



Species 30, chiefly in Mex. and S. W. United States. 



B. oligostachya (Nutt.) Torr. is the Grama-grass of U. S. prairies; B. 

 hirsuta Lag., hairy Mesquite-grass. 



B. MEGAPOTAMICA (Spr.) O. Ktze. (B. multiseta Gris.) 

 Cespitose; culms creeping, ascending, jointed, simple, 30 cm. tall. 

 Leaves linear, narrowing subulate at top, the margins rough, glaucous 

 above ; their sheaths cleft, glabrous, and ligules short ciliate. Spikes 3-4, 

 racemose. Spikelets 4-5-flowered, silky at base ; lower flower 3-awned, 

 densely pilose; the others with one glume and 9-11 fascicled awns. 

 (Brazil; Argentina.) N. Patagon. along Rio Negro, near Carmen. 



37. TETRAPOGON Desf. (Cry ptoc Moris Benth.) 

 Small grasses, with dense simple spike half enclosed within a spathe-like 

 bract. Spikelets with 1-2-3 flowers, silky. Lower glumes very narrow, 

 acute, awnless ; several upper empty glumes smaller and awned ; floral 

 glume awned, the awn terminal between 2 obtuse lobes, mostly silky. 

 Floral glume and grain falling away together. 

 Species 6, chiefly African ; i in Patagon. 



T. SPATHACEUS (Benth.). 



Annual grass, scarcely 5 cm. high; stems below the inflorescence, 12-25 

 mm. Leaves few, laxly sheathing, the blades linear. Bract large, spathe- 

 like, 16-20 mm. long, nearly enclosing the sessile, continuous, subsecund 

 spike, which is quasi-plumose from the setce and awns of the 2-flowered, 

 biseriately crowded spikelets. 



S. Patagon., by Rio Sta. Cruz. "My specimens hardly differ from the 

 description by the palea being awnless and attenuate-mucronate." (Speg.) 



38. PAPPOPHORUM Schreb. 



Cespitose grass, with narrow, often convolute leaves, and dense spici- 

 form panicle, with many awns often silk-like. Spikelets 1-2-, rarely 3-4- 



