This widespread southern species is the only perennial Setaria in Ky., and the only potential native member of the genus; 2n = 36 and 72 (FNA 25). However, it may be adventive in the state; the earliest verified records appear to come from TODD in 1949 (APSC) and MARS in 1954 (CM). Some colls. without roots are difficult to distinguish from pumila, and should be rechecked. In addition 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 often glaucous leaves (versus usually plain green).