This widespread southern species is the only perennial Setaria in Ky., and the only native member of the genus; 2n = 36 and 72 (FNA 25). Some colls. without roots are difficult to distinguish from pumila, and should be rechecked. In additional to its short knotty rhizomes (versus annual roots), parviflora differs from pumila in its usually shorter spikelets (minus awns, 2-2.8 mm versus 3-3.4 mm), its frequenly shorter spikes (up to 8 cm versus 15 cm), usually less deeply yellowish bristles (versus clearly yellowish), and its frequently glaucous leaves (versus usually plain green).