Plants perennial; cespitose, forming clumps 4-10 cm in diameter, without
rhizomes or stolons. Culms 20-35(50) cm, stiffly erect. Leaves
bluish-green, more or less glaucous; sheaths mostly glabrous, hairs present
distally; ligules 1-1.5 mm, of hairs; blades 5-15(25) cm long,
1-1.5(2.5) mm wide, stiffly erect or curving, involute when dry; mostly glabrous,
ligular area with long and short hairs, bases usually with papillose-based hairs
on the margins. Panicles 5-13(20) cm, with 9-15(30) branches; branches
4-5.5 mm, deciduous, scabrous, with 2-6 spikelets, axes terminating well beyond
the terminal spikelets, apices entire; disarticulation at the base of
the branches. Spikelets 5-6.5 mm, with 1 bisexual and 1 sterile floret,
appressed, all alike, green, often with a brownish or purplish cast. Lower
glumes slightly shorter than the upper glumes, both usually exceeded by
the lemmas of the lowest florets; upper glumes glabrous, sometimes scabrous;
lowest lemmas glabrous, acute, 3-awned, awns less than 1 mm, central
awns not flanked by 2 membranous lobes; anthers 2.2-3.7 mm, dark purple;
second florets sterile, usually without paleas; second lemmas
reduced to a glabrous awn column, sometimes moderately well-developed and 3-awned,
awns usually not exserted, central awns to 2.5 mm. 2n = 21, 22, 23, 24,
25, 28, 38, 40.
Bouteloua warnockii grows on limestone ledges and dry slopes below limestone
outcrops. Its range extends from the southwestern United States to the state
of Coahuila in northern Mexico. It frequently grows, and may hybridize with,
B. curtipendula var.
caespitosa.