Hybridization may increase the risk of extinction for some rare and endangered plant species, either by increasing the rate of random genetic drift affecting populations or by introgression-mediated genetic assimilation. The former may occur when hybrids are less fit than nonhybrids and backcrossing would be less likely to occur, the latter may occur when hybrids are as fit, or fitter, than parents, and backcrossing is fairly common. To assess the risk of extinction by hybridization one must assess whether hybridization is actually occurring, and, if so, whether the hybrids are sterile, or are backcrossing. We analyzed one population each of the rare Liatris oligocephala and L. cylindracea and seven field-identified hybrids for ribosomal DNA and chloroplast DNA markers, and morphological characteristics to make a preliminary determination of the potential for L. oligocephala extinction via hybridization. We found unequivocal evidence that the two species are hybridizing, but no unequivocal evidence of backcrossing.