542 



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



FiGT-tRE 788. — Bouteloua eriopoda. Plant, X 1; spike- 

 let, X 5. (Hitchcock 13357, Tex.) 



Figure 7S9. — Bouteloua trifida. Panicle, X 1; spike- 

 let, X 5. (Amer. Gr. Natl. Herb. 669, Tex.) 



lobes; rudiment densely bearded at 

 summit of rachilla joint, cleft nearly 

 to the base, the rounded lobes ob- 

 scured in the dense hairs. 01 (B. 

 ramosa Scribn.) — Gypsum sands and 

 calcareous rocks, western Texas, New 

 Mexico, and northern Mexico. Re- 

 sembling B. gracilis but with loose, 

 woody base and wiry culms; rachis 

 prolonged and bearing a rudimentary 

 spikelet at the tip. 



17. Bouteloua eriopoda (Ton.) 

 Torr. Black grama. (Fig. 788.) 

 Perennial; culms tufted, with swollen 

 bases, slender, wiry, widely spreading 

 with arched internodes or stolonifer- 

 ous, white-lanate, 40 to 60 cm. long; 

 blades 1 to 1.5 mm. wide, nexuous; 

 spikes 3 to 8, commonly -1 or 5, 

 loosely ascending, 2 to 3 cm. long; 

 spikelet s 12 to 20, not crowded and 

 pectinate, 7 to 10 mm. long, narrow; 

 fertile lemma acuminate, with a 

 terminal awn, the lateral minute or 

 obsolete; rudiment slender, cleft near- 

 ly to the base, the awns equaling the 

 awn of the fertile lemma, the lobes 

 minute, narrow. 91 — Mesas, hills. 

 and dry open ground, Oklahoma and 

 Texas to Colorado, Utah, southern 

 California, and northern Mexico. 



18. Bouteloua trifida Thurb. (Fig. 

 789.) Perennial, tufted, leafy at base, 

 rather delicate; culms erect, 10 to 

 20 cm. tall; blades usually only 1 to 

 2 cm. long; spikes 3 to 7. 1 to 2 cm. 

 long, ascending or appressed; spike- 

 lets about 12, purplish, 7 to 10 mm. 

 long; fertile lemma pubescent toward 

 base, cleft more than half its length, 

 with awns [o mm. long) winged 

 toward base and no intermediate 

 lobes; rudiment cleft to the base, the 

 awns similar to those of the fertile 

 lemma, about as long. % (B. 

 trinii Griffiths; B. burkii Scribn.) — 

 Mesas, ravines, and rocky hills, 

 Texas to Nevada and Arizona; Cali- 

 fornia (Death Valley) ; northern Mex- 

 ico. Variable in length of the awns, 

 the type of B. trifida being the 

 longer awned form. 



