The midwestern range of this species is centered on Mo., Iowa and Ill. but with somewhat disjunct populations east to se. N.Y., n. Va., w. Ky. and c. Tenn (K). Although some initial identifications in Ky. have been tentative or erroneous (e.g. from BELL, MENI and PIKE), the species is verified fron LIVI (KY) and LYON (APSC). D. obovata is generally distinct from typical americana in its lemmas (FNA 24, W): glabrous on the basal callus (versus hairy on all but lowest lemmas), generally shorter (mostly 4-7 mm versus 5-10 mm), obovate or elliptic (versus lanceolate), and abruptly (versus gradually) tapering to the apex. Also fruits are wider (1.8-2.5 mm versus 1.3-1.8 mm) with a more abrupt "bottlenose" beak (versus broad, blunt beak), and usually stramineous except for basal brown areas (versus brownish to black except for the stamineous beak). Intermediates have not been demonstrated; 2n = 60 in obovata but still unknown in americana (FNA 24). Further records of obovata are expected in western and northern regions of the state, since the species is known in adjacent north-central Tenn (Ch), suggesting dispersal long the lower Cumberland Rv. valley, and in s. Ohio (K). It is common at Shawnee Lookout in Hamilton Co., Ohio, within 5 miles of n. Ky. (D. Boone, pers. comm.). The species may be generally concentrated on gravelly alluvial terraces (base-rich but seasonally dry), whereas americana mostly occurs on calcareous slopes (W); but more ecological data are needed.