Penstemon (Plantaginaceae) is one of the most diverse endemic genera to North America, and a relatively recent radiation with more than 270 described. A survey of its genome structure and size variation showed that most species are diploid, but they still exhibit a remarkable 2-fold variation in genome size without any change in chromosome number. Different varieties within Penstemon pachyphyllus have been found to differ in phylogenetic position and genome size, suggesting that they represent different taxa. The main objective of this project is to test monophyly of P. pachyphyllus using phylogenetic methods applied to 20 populations representing its geographic range. The REU intern is expected to get involved in all aspects of research and will gain experience in DNA extraction and amplification in the lab, and computer based phylogenetic analyses.