540 



MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



commonly 1 to 1.5 cm. long; spikelets 

 similar to those of B. hirsuta, but 

 the awns of the rudiment somewhat 

 longer, the spikes more bristly. % 

 B. hirticulmis Scribn. — Rocky hills, 

 prairies, and open ground, Arizona 

 (Santa Cruz County) ; Mexico. 



Figure 784. 



—Bouteloua glandulosa. Panicle, 

 (Type of B. hirticulmis.) 



X 1. 



14. Bouteloua hirsuta Lag. Hairy 

 grama. (Fig. 785.) Perennial, densely 

 tufted; culms erect, 20 to 60 cm. tall, 

 leafy at base; blades flat or sub- 

 involute, about 2 mm. wide, flexuous; 

 spikes 1 to 4, usually 2, 2.5 to 3.5 

 cm. long, the rachis extending be3 r ond 

 the spikelets as a slender point 5 to 

 8 mm. long; spikelets 35 to 45, about 

 5 mm. long, second glume tubercu- 

 late-hirsute with spreading hairs, the 

 tubercles black; fertile lemma 3-cleft, 

 the divisions and margins of lemma 

 pubescent, awn-tipped; rudiment from 

 puberulent to bearded at summit of 

 rachilla, cleft nearly to the base, the 

 lobes firm, broad, spreading, the 

 awns black. % — Plains and rocky 



hills, Wisconsin and North Dakota 

 to Texas, Colorado, Arizona, and 

 California (Jamacha), south through 

 Mexico; also peninsular Florida. 

 Bouteloua pectinata Featherly was 

 differentiated from B. hirsuta by 

 taller more robust culms and by a 

 rudimentary spikelet at the end of 

 the rachis. Such a spikelet is rarely 

 developed in B. hirsuta, but it is not 

 correlated with robust plants. 



15. Bouteloua gracilis (H. B. K.) 

 Lag. ex Steud. Blue grama. (Fig. 

 786.) Perennial; densely tufted; culms 

 erect, 20 to 50 cm. tall, leafy .at base; 

 blades flat or loosely involute, 1 to 2 

 mm. wide; spikes usually 2, sometimes 

 1 or 3, rarely more, 2.5 to 5 cm. long, 

 falcate-spreading at maturity, the 

 rachis not projecting beyond the 

 spikelets; spikelets numerous, as many 

 as 80, about 5 mm. long; fertile 

 lemma pilose, the awns slender, the 

 intermediate lobes acute; rudiment 

 densely bearded at summit of 



Figure 785. — Bouteloua hirsuta. Panicle, X 1; spike- 

 let, X 5. (Griffiths 3371, Ariz.) 



