Setaria villosissima
Plants perennial; cespitose. Culms 40-100 cm. Sheaths villous distally, margins ciliate; ligules about 1 mm, densely ciliate, hairs white; blades 15-30 cm long, 5-8 mm wide, both surfaces villous. Panicles 10-20 cm, loosely spicate; bristles usually solitary, 10-20 mm. Spikelets 2.8-3 mm. Lower glumes about 1/3 as long as the spikelets, broadly ovate, 3-veined; upper glumes nearly equaling the spikelets, 5-7-veined; lower lemmas equaling the upper lemmas, 5-veined; lower paleas about 1/5 as long as the upper paleas, lanceolate; upper lemmas finely and transversely undulate-rugose basally, striate and punctate distally; upper paleas similar, ovate-lanceolate. 2n = 54.
Discussion
Setaria villosissima is a rare species that grows on granitic soils in southwestern Texas and northern Mexico. The villous sheaths and blades and large spikelets of S. villosissima aid in its identification. A.S. Hitchcock's (1951) report of Setaria villosissima from Arizona is based on misidentification of a specimen of S. leucophila (Reeder 1994).