Penstemon bicolor ssp. bicolor is endemic to the Spring Mountains of Clark County, Nevada. It has been designated a sensitive species threatened by urban growth in the Las Vegas Valley, which is resulting in habitat degradation and loss. We used ISSR markers to assess the amount of genetic diversity present in populations of P. bicolor ssp. bicolor, and we compared the genetic diversity of ssp. bicolor to the widely distributed ssp. roseus. Two hundred ninety five individuals from seven populations of P. bicolor ssp. bicolor, six populations of P. bicolor ssp. roseus, and several populations of P. palmeri were used in the survey. Our results suggest that the amount of genetic divergence between the two subspecies of P. bicolor is relatively low and that average similarity between subspecies is the same as within subspecies.

Key words: conservation genetics, Inter-SSR, ISSR, molecular markers, Penstemon, Scrophulariaceae