Bouteloua barbata var. rothrockii
Plants short-lived perennials; not stoloniferous. Culms 25-60 (75) cm, stiffly erect or slightly geniculate-spreading basally; ligules 0.1-0.5 mm; blades 6-10 cm long, 1-4 mm wide. Panicles (3.5) 5-25 cm, with 3-8 branches; branches 15-30 mm, scabrous, with 35-50 (55) spikelets. 2n = 40.
Bouteloua barbata var. rothrockii grows on dry slopes and sandy flats, mostly at 750-1700 m. It grows throughout the southwestern United States and Mexico, sometimes covering large areas. It used to be the most important forage grass in southern Arizona and neighboring regions.
Bouteloua barbata var. rothrockii resembles B. parryi var. parryi, but can be easily distinguished from that taxon by the lack of papillose-based hairs on the keels of its upper glumes.
"decumbent" is not a number.