Hybrids ofAletris lutea XA. obovata were found to occur extensively throughout the area of overlapping distribution of the two species in Florida and in southern Georgia. Hybrids were found only in disturbed habitats near the parental species. Colonization and dispersal of species and of hybrids were probably implemented by roadside maintenance operations. Fertility was high despite the high incidence of quadrivalent formation in parent and hybrid plants. Since all quadrivalents observed were aligned adjacently and since fertility is relatively high, it is suggested that duplicated chromosomes were present. It is further suggested thatAletris represents a tetraploid with a base number ofx = 6 or 7 that either lost or gained one pair of chromosomes to result inn = 13. Introgression in disturbed habitats is favored by zonation of plants in hybrid swarms, phenology of parents and hybrids, and pollinator behavior.