Penstemon, with nearly 300 species, is the largest genus of plants that are found only in North America. It is also a relatively young genus, originating in the last 2–3 million years. Penstemon is an example of a rapid evolutionary radiation in a continental setting — a rare pattern in plants. Species of Penstemon are adapted to many different soils, have pollinator specialization, and tend to occur in pioneer or marginal communities. The combination of a rapid evolutionary radiation and adaptation to specialization in pollinators and ecosystems has resulted in a significant number of rare and threatened species, including several that have been listed as Federally endangered or threatened. We aim to study relationships among species and populations in Penstemon. This will entail both conservation genetics, morphology, and pollination ecology.