Packera millefolium is a rare species endemic to rock outcrops in the southern Appalachians thought to hybridize with its more common congener, P. anonyma. Morphological analyses and cross-pollination experiments were used to verify the existence of the hybrid Packera ×memmingeri. Preliminary results show that introgression between P. millefolium and P. anonyma is probable at some locations. Information on population size and the presence or absence of hybrids was compiled for populations of P. millefolium from historical records and on-site surveys. An analysis of this data shows that hybrids occur at approximately 40% of the populations in North and South Carolina. The data also suggests that anthropogenic disturbance of the landscape surrounding once isolated populations of P. millefolium might have broken down the ecological barriers that historically prevented gene flow between P. millefolium and P. anonyma. The management implications for P. millefolium due to hybridization with P. anonyma are discussed.