This occurs on dry soils in northeastern and Appalachian regions, perhaps concentrated on calcareous soils. Distinction from catesbeiana has been generally ignored in Ky. until recent revision by R.K. Brummitt (FNA in prep., see W). The transition has been rather poorly understood, being mapped close to the boundary from Ky. and Va. to Tenn. and N.Car. (K, W). Variation iwthin this complex needs more attention for mapping in Ky. C. purshianus (= C. spithameus var. pubescens (Gray) Fern. or ssp. stans (Michx.) Brummit) is known from southern Appalachian regions, especially on shale in the Ridge-and-Valley, and it may be expected in Ky. It is generally tomentose (versus glabrous to pubescent); leaves are more folded and have larger lobes (W). Var. pubescens can appear transitional to C. catesbeiana or, if densely white-tomentose, C. sericata (House) Bell, which may also be expected (W).