Morphometric and genetic variation were assessed in populations of Eriocaulon koernickianum Van Heurck & Muller-Argoviensis, an uncommon species that is disjunct between the southern Appalachian and the Ozark and Ouachita Mountains, and adjacent regions. The eastern populations possessed smaller and fewer leaves and flowering scapes than the western populations. However, no discontinuities in floral morphology were apparent between populations from the two geographic regions. Furthermore, little genetic variation or divergence, as measured by isozymes, was observed within or among populations, suggesting that a genetic bottleneck occurred in the recent past in this predominantly-outcrossing species. The limited genetic variation suggests that simple vicariance and contemporary long distance seed dispersal are unlikely, and instead that fragmentation and recolonization (perhaps following the Pleistocene epoch) may explain the current biogeography.