I study plant systematics, reproductive biology, and phylogeny, with special emphasis on the Rosaceae (the rose family) and Pinaceae (the pine family). Along with collaborators, I am interested in the molecular phylogeny of these families based on sequences from multiple genes. Current focus is on one of the genera of the rose family, Amelanchier (the shadbushes or serviceberries), which has long challenged systematists with its unclear species boundaries and complex patterns of morphological variation. These small trees and shrubs also provide a model for the evolution of apomixis (asexual seed production). Research goals include identifying the relevance of apomixis and polyploidy to patterns of variation, understanding the biology of apomixis, establishing a workable species concept, and developing a tractable species classification. We are also involved in working out the tree of life for the Pinaceae and related plants. Research techniques include field studies, DNA sequencing, phylogenetic analyses, quantitative morphology, and studies of breeding systems. Graduate students I have advised have used these techniques to study problems in these groups and other groups as well.