This is largely restricted to rocky calcareous woods, especially along clifftops, on the southern Interior Low Plateaus, Gulf Coastal Plain and in hills around the Southern Appalachians (K, W). The species is unknown in Ark., Mo., Ill., Ohio abd W.Va., but there is a potential wild record from se. Ind. (Jefferson Co.). H. frondosum is similar to prolificum, but has larger flowers (with petals mostly 10-20 mm long versus 7-15 mm), usually solitary in the inflorescence (1-3 versus 3-7 flowers); also, its leaves are distinctly glaucous and tend to have broader shape (Sm, F, J, W). Plants usually do not exceed 1-2 m, but prolificum is often 2-3 m tall. H. frondosum has been widely used in horticulture (and locally escaped in more eastern states), but not enough yet in Ky.