This is a largely Ozarkian species, but it is also known from a few scattered locations across southeastern states, usually in rocky woods on base-rich soils (W). Variation needs further attention; 2n = 18 and 36 (FNA 20). The only record from Ky. may be a coll. from Eastview Road ca. 0.3 miles east of railroad in HARD: "badly disturbed oak woods, south side" (Cranfill & Medley 1981; M). A duplicate of this coll. has been recently accessed at EKY, and Cranfilll's material is stored at KNK. The locality has been researched many times with no success. Cronquist (Cr) may have confirmed the coll. since he included w. Ky. in the range of radula; see also FNA 20. Identity of the Cranfill & Medleyi remains uncertain, perhaps being close to radula but also suggesting ulmifolia; hybridization is possible. Although generally classified in Nemorales (with nemoralis), radula appears similar to some species of the Triplinerviae (especially rupestris; see W).