My research program encompasses vascular-plant systematics, floristics, and conservation biology, with an emphasis on biosystematic and phylogenetic studies. I am particularly interested in systematic questions that address evolutionary processes, historical biogeography and ecology, and relationships of California plants and their descendant lineages elsewhere (e.g., Hawaii). My research on the California tarweeds and the Hawaiian silversword alliance (Compositae: Madiinae) has involved testing of hypotheses concerning diversification processes and rates, chromosomal and morphological evolution, ecological shifts, dispersal events, and the evolutionary importance of hybridization. I am also involved in collaborative investigations focused on evolution of breeding and pollination systems in flowering plants. Laboratory techniques used in my research include DNA sequencing and cytogenetic and morphological analyses. Recent theoretical and technological advances in systematics offer exciting opportunities for studies of California plant evolution and relationships. The rich diversity of the California flora and the extensive literature from evolutionary research on California plants pose well-defined and important systematics research problems for graduate study.