MANUAL OF THE GRASSES OF THE UNITED STATES 



535 



773.) Resembles slender forms of B. 

 curtipendula, culms slender, wiry, 

 sometimes with slender stolons, the 

 slender blades subinvolute, the spikes 

 8 to 9 mm. long, with 1 or 2 spikelets, 

 the scabrous rachis mostly longer 

 than the first glume; lemma awnless; 

 rudiment reduced to a single awn ap- 

 pressed to the back of the palea. % 

 —Rocky hills and valleys, central and 

 western Texas. 



3. Bouteloua curtipendula (Michx.) 

 Torr. Side-oats grama. (Fig. 774.) 

 Perennial, with scaly rhizomes ; culms 

 erect, tufted, 50 to 80 cm. tall; blades 

 flat or subinvolute, 3 to 4 mm. wide, 

 scabrous; spikes 35 to 50, 1 to 2 cm. 

 long, purplish, spreading or pendulous 

 and mostly twisted to one side of the 

 slender axis, this 15 to 25 cm. long; 

 spikelets 5 to 8, appressed or ascend- 

 ing, 6 to 10 mm. long; fertile lemma 

 acute, mucronate; rudiment with 3 

 awns and subacute intermediate 

 lobes, often reduced and inconspicu- 

 ous. % (Atheropogon curtipendulus 

 Fourn.) — Plains, prairies, and rocky 

 hills, Maine and Ontario to Montana, 

 south to Virginia, Alabama, Texas, 

 Arizona, and southern California; 

 South Carolina (introduced); Mexico 

 to Argentina. 



4. Bouteloua rigidiseta (Steud.) 

 Hitchc. (Fig. 775.) Perennial, tufted, 

 leafy at base; culms erect, 20 to 30 

 cm. tall; blades narrow, flat or some- 

 what involute, 1 to 1.5 mm. wide, 

 sparingly papillose-pilose; spikes 6 

 to 8, triangular-cuneate, spreading, 

 about 1 to 1.2 cm. long including the 

 awns; spikelets mostly 2 to 4, 

 crowded, ascending; glumes pubes- 

 cent; fertile lemma with 3 spreading 

 awns, the intermediate lobes acute; 

 rudiment with stout spreading awns, 

 much exceeding those of the fertile 

 lemma, the intermediate lobes firm, 

 pointed, a second similar but smaller 

 rudiment commonly developed. % 

 (B. texana S. Wats. ; Polyodon texanus 

 Nash.) — Plains and rocky hills, Okla- 

 homa, Texas, and northern Mexico. 



5. Bouteloua eludens Griffiths. 

 (Fig. 776.) Perennial, densely tufted, 



Figure 775. — Bouteloua rigidiseta. Panicle, X 1; 

 spikelet, X 7; lemma and florets, X 5. (Griffiths 

 6370, Tex.) 



leafy at base; culms erect, 25 to 60 

 cm. tall; blades mostly 1 to 1.5 mm. 

 wide; axis slender, flexuous, 6 to 8 

 cm. long; spikes 10 to 20, triangular, 

 spreading, about 1 cm. long including 

 the awns; spikelets about 5; rachis 

 and glumes densely pubescent ; fertile 

 lemma pubescent toward the summit, 

 the apex 3-cleft, the divisions awn- 

 tipped; rudiment with stout pubes- 

 cent awns about 5 mm. long, the long- 

 narrow intermediate lobes glabrous ; a 

 second similar but smaller rudiment 

 usually developed. % — Rocky 

 hills, southern Arizona and Sonora, 

 Mexico. 



