This is endemic to the southern Appalachians, where it generally occurs under cliffs of non-calcareous rocks. Records from MCRE and PULA are tentatively based on inadequate colls., but detailed in reports to Daniel Boone National Forest (Campbell et al. 1994). M.S. Lanning (2009, M.S. thesis, Western Carolina Univ.) and W have recently supported the generic placement of Sm that is followed here.