My research focuses on the ecological and evolutionary questions concerning plant reproduction. My students and I study the processes that generate and maintain genetic variation in characters important for reproductive success of plants in natural populations. We combine observation from natural populations, manipulative experiments in the greenhouse and in common gardens, quantitative genetics, and molecular evolution approaches in our studies. Though I consider myself an empirical biologist, I am very fond of theoretical studies, and have occasionally done some theoretical investigation for factors difficult to study empirically. Three current focus areas in my group are: (1) Maintenance of gynodioecy in the wild geranium, Geranium maculatum, (2) Sexual selection in hermaphroditic plants, focusing on pollen size as a male trait (Ipomoea purpurea), and (3) Evolution of herbicide resistance in agricultural weeds (Ipomoea purpurea).