In Ky., this northeastern taxon is virtually unknown west of Appalachian regions; there is a disjunct population in sandstone ravines of EDMO and perhaps HART. Further study of colls. is needed to clarify separation of varieties in this largely diploid (2n = 18) species. See also notes on its polyploid relatives, harrisii (2n = 36) and faucibus (2n = ca. 90).