Broadly defined, this complex species is widespread on xeric base-rich sites across North America, with several regional or local segregates that can be recognized (SC, W; R. Dever & D. Ford-Werntz, pers. comm.). Some plants in w. Ky. (including rocky glades of LOGA) appear more robust and flower later, suggesting a transition to stellatum, but without the spreading stellate tepals of that species. See also notes under stellatum, which may has been confused in some cases; 2n = 14 in both species. With some biogeographic parallels, cryptic variants may also exist among associated xerophytic calciphiles in Sedum, Mononeuria, Cerastium, Houstonia, Rudbeckia, Echinacea and Sporobolus. The coll. from PIKE (F. Levy in 1984 at NCU) should be checked for possible A. allegheniense Small; see Dever (2014) and W.