No. 40. 

 BOUTELOUA TRIFIDA Thurber. 



Culms 6 to 12 inches long, slender, numerous, crowded on a short rootstock; base 

 often thickened, covered with short, broad sheaths. 



Leaves; blades small, radical sometimes 2 or 3 inches long, those of the culm 

 often reduced to \ inch, smooth or sparsely hairy; sheath shorter than the 

 internode. 



Inflorescence of 4 to 6 erect or somewhat spreading smooth spikes, with about 

 15 to 30 spikelets rather loosely disposed. 



Spikelets 3 lines long including the awns, containing 1 perfect and 1 imperfect 

 flower. 



Empty glumes slightly unequal; upper 1^ lines long; lower one-fourth shorter, 

 smooth, 1 -nerved; flowering glumes narrow, body oblong, smooth, less than 1 

 line long, dividing above into 3long-awned lobes (2 to 2| lines long). 



Palet somewhat shorter and narrower than its glume, 2-toothed at the apex. 

 Imperfect flower reduced to 3 slender awns slightly enlarged toward the base, 

 on a short, smooth pedicel. 



Plate XLVI; a, spikelet; b, empty glumes; c, flowering glume; d, palet; e, 

 imperfect flower. 



This species closely resembles B. Burkei, No. 36, but a close comparison shows 

 important differences. 



