538 



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



Figuee 780. — Bouteloua simplex. Plant, X 1; spikelet, 

 X 5. (Griffiths 7362, Ariz.) 



long, strongly arcuate at maturity; 

 spikelets mostly 20 to 30, about 5 

 mm. long; fertile lemma pilose at base 

 with stout awns and subacute inter- 

 mediate lobes; rudiment bearded at 

 summit of rachilla-joint, cleft to the 

 base or nearly so, the awns equal, a 

 second rudiment, broad and awnless, 

 sometimes developed. O (B. pro- 

 cumbens Griffiths.) — Open ground, 

 Texas to Colorado, Utah, Arizona, 

 and Mexico; wool waste, Maine; 

 Ecuador to Argentina. 



10. Bouteloua barbata Lag. Six- 

 weeks grama. (Fig. 781.) Annual, 

 tufted, branching, erect to prostrate, 

 often forming mats with ascending 

 ends, the culms as much as 30 cm. 

 long; foliage scant; blades 1 to 4 cm. 

 long, 1 to 1.5 mm. wide; spikes 4 to 



7, 1 to 2 cm. long; spikelets 25 to 40, 

 2.5 to 4 mm. long, nearly as broad; 

 fertile lemma densely pilose at least 

 along the sides, usually throughout, 

 the awns from minute to as long as 

 the body, the intermediate lobes sub- 

 acute to obtuse; rudiment from ob- 

 scurely to conspicuously bearded at 

 summit of rachilla joint, cleft nearly 

 to the base, the intermediate lobes 

 broad, subcucullate, the awns of rudi- 

 ment and fertile lemma reaching 

 about the same height, a second rudi- 

 ment, broad and awnless, often de- 

 veloped. O (B. microstachya L. H. 

 Dewey.) — Open ground, mesas, and 

 rocky hills, Texas and Colorado to 

 Nevada and southeastern California; 

 Mexico. The awns vary in length. 

 The form with shorter awns is that 

 described as B. pumila Buckl. ; the 

 longer awned form is that described 

 as B. arenosa Vasey. 



11. Bouteloua parryi (Fourn.) 

 Griffiths. Parry grama. (Fig. 782.) 



Figuee 781. — Bouteloua barbata. Plant, X 1; spikelet, 

 X 5. (Griffiths 6095, Ariz.) 



