No. 40. 

 BOUTELOUA HUMBOLDTIANA Kunth. 



Culms erect, rarely branching, firm, 15 to 20 inches high, smooth, leafy below. 



Leaves: sheath open, striate, shorter than the internodes; ligule inconspic- 

 uous; blade 1 to 2 lines wide, 3 to 6 inches long, scabrous especially on the mar- 

 gins, often sparsely ciliate below. 



Inflorescence racemose, 3 to 4 inches long, consisting of about 7 to 9 one-sided, 

 short- pedicelled spikes, lower ones - inch or more distant, others gradually shorter; 

 spikes about $ inch long, each consisting of 7 to 9 smooth spikelets, somewhat 

 loosely overlapping each other. 



Spikelets about | inch long, including the awns, smooth, consisting of 2 to 3 

 flowers, upper male, others perfect, or the lower 2 fertile and the upper reduced 

 to an awn. 



Empty glumes nearly equal, 3 to 4 lines long, keeled, lanceolate, acute; flower- 

 ing glume of the lower flower 4 lines- long, lanceolate, 3-nerved, 3-toothed, at the 

 apex of the second flower similar, but with the teeth extended- into long awns (2 

 to 3 lines long). 



Palet nearly as long as the glume, 2-nerved, 2-toothed at the apex. Third 

 flower when present, sometimes with awns still longer, or imperfect or reduced. 



PLATE XL: a, spikelet; 6, empty glumes; c, flowering glume of the fertile 

 flower; d, palet of the fertile flower; c', flowering glume of the second flower; d', 

 palet of the second flower. The sterile flower reduced to a small pedicel is seen in a. 



It is doubtful whether this plant, which has passed under the name B. Hum- 

 boldtiana, is really identical with that described by Kunth. Our plant is more 

 probably a form of B. bromoides Lag. In range it seldom extends north of New 

 Mexico. 



