Plants annual; tufted. Culms 4-60 cm, outer culms of a tuft decumbent, sometimes geniculate, branched at the lower nodes. Ligules 0.2-0.5 mm, membranous, lacerate or ciliate; blades 2-5 (9) cm long, 0.7-2 mm wide, flat or folded, adaxial surfaces sometimes with papillose-based hairs, margins usually with papillose-based hairs near the ligules. Panicles 2.5-10.5 cm, with (1) 4-15 branches; branches 5-45 mm, deciduous, densely pubescent (at least basally), with 2-10 spikelets per branch, axes extending 2-10 mm beyond the base of the terminal spikelets, apices entire; disarticulation at the base of the branches, the break forming a sharp tip. Spikelets appressed. Proximal spikelet on each branch with 1 floret; lower glumes 1.5-3.5 mm, glabrous, narrow to subulate; upper glumes 5.5-6.2 mm, densely pubescent, at least on the basal 1/2; lemmas 5.8-6 mm, acuminate, unawned; lowest paleas almost as long as the lemmas, bifid, glabrous; rachillas prolonged beyond the florets for about 0.5 mm. Distal spikelets with 1 bisexual and 1 rudimentary floret, glumes unequal, glabrous, minutely scabrous on the keels; narrowly acute or acuminate; lower glumes 1.5-2 mm; upper glumes 5-6 mm, glabrous or sparsely pubescent basally, often divergent; lowest lemmas 6-8 mm, veins pubescent, lateral-veins excurrent as short (to 1 mm) awns, acuminate, midvein extended into a setaceous tip or a short awn; lowest paleas 5-7 mm, bifid, veins often excurrent as short awns; anthers about 2.5 mm, yellow or yellow and red; distal florets reduced to a pubescent, 3-awned, awn column, awns 2-7 mm, exserted. Caryopses 2.5-3 mm. 2n = 40.
Md., N.Mex., Tex., Utah, Calif., Ariz., Nev.
There are two varieties, both of which grow in the Flora region.
|1||Panicle branches with 2-5 spikelets, usually 5-16 mm to the base of the terminal spikelets, axes usually extending an additional 6-10 mm||Bouteloua aristidoides var. aristidoides|
|1||Panicle branches with 6-10 spikelets, usually 15-35 mm to the base of the terminal spikelets, axes extending an additional 2-5(7) mm||Bouteloua aristidoides var. arizonica|
"decumbent" is not a number.