Morphological and cytological variation in Aster acuminatus Michx. was observed in populations located in the southern Appalachians. Results indicated that A. acuminatus in closed, shady habitats had morphological variation typical of the species, with normal meiosis and high pollen stainability. A. acuminatus in open, exposed habitats was more variable morphologically, with abortive meiotic figures and low pollen stainability. The variation was indicative of genetic contact with Aster nemoralis Ait., which is sympatric with A. acuminatus in the northeastern United States, but absent in the southern Appalachians.