This upper midwestern species has disjunct eastern populations on limestone clifftops in s. Ohio, c. Ky., c. Tenn., and w. Va. (FNA 25). The record from Panther Rock in ANDE (Bryant 1973) needs to be verified. At Grassy Knob in ESTI, capillaris occurs on ledges above cuspidata. These two species, and other cespitose "muhly-grasses" in Ky. (mostly with 2n = 20 or unknown), are quite distinct in morphology and habitat from the regular rhizomatous species of this genus (mostly with 2n = 40).