This variable species (2n = 10, 20) is widely distributed from east-central states to the Great Plains (K) but restricted to xeric rocky calcareous sites, usually in thin woods and small openings along bluffs. In Ky. most records are from extensive limestone cliffs along or near the Palisades of Kentucky Rv. (and tributaries), and along the western edge of the Appalachian Plateaus. It remains unknown within the Green Rv. watershed, but does occur further south along the Cumberland Rv. (Ch). With several cultivars, the species has also become widely planted, especially in rock gardens.