XVI International Botanical Congess

Phlox pilosa L. (Polemoniaceae) is a highly variable species with a complicated evolutionary history. In the Ozark highlands of Arkansas and Missouri, striking morphological variation has led to the recognition of a distinct subspecies, P. pilosa subsp. ozarkana (Wherry) Wherry. This research addresses the hypothesis that some of the variation within P. pilosa subsp. ozarkana is due to introgression between P. pilosa subsp. pilosa and P. divaricata L. in the topographically complex Ozark region. A gene tree based on a region of single-copy" nuclear DNA (part of that containing the glyceraldehyde 3-phosphate dehydrogenase gene) is presented. The patterns of relationship are intriguing, and are discussed with respect to geography, morphology and taxonomic status of samples. Ongoing research includes development of additional gene trees for comparison.