This diploid (2n = 60) occurs in rocky woods and glades across east-central states, concentrated in the Ozarks and Appalachians, and generally on rocks with intermediate base-status (W). The related apogamous triploid (2n = 90),.M. tomentosa (Link) Fée, is concentrated in southwestern mountains, the Ozarks and southern Appalachians. It has been found in c. Tenn. but remains unknown in Ky. (Ch+, K).