This is a widespread, variable northeastern species of mesic to submesic woods on acid soils. Within Ky. and Tenn. it is largely restricted to Appalachian regions, but disjunct plants have been identified in gravelly hills on the west side of the Mississippian Plateaus. C. gracillima is a variable species (2n = 50, 52, 54) that is reputed to form sterile hybrids with several related species (FNA 23). The potential for confusion or intergradation with oxylepis, in particular, needs further investigation.