This taxon was described from the Knobs and other hills just west of the Appalachian Plateaus in. n. Ky. and se. Ohio (F), and it also seems to occur locally from n. Miss. to n. Ga. (pers. obs.). Var. lucy-brauniae is identified simply by its glabrous upper leaf surfaces (versus scabrous), but some colls. in the western Knobs are not clearly distinct. Apparent hybrids with trifoliatum have been collected from FLEM (EK) and ROWA (JC). Based on label data, var. luciae-brauniae appears to have been locally abundant as late as 1920-1950 in the calcareous or dolomitic foothills between the eastern Knobs and western Bluegrass region, where narrow strips of grassland occurred before settlement. Although there are virtually no intact remnants of that vegetation, this Silphium and other conservative associates do survive in a few rights-of-way and old fields that have not been converted to fescue or subjected to intense browsing. There are also scattered patches below limestone cliffs within the Knobs.