We study plant-pollinator interactions from nutritional and cognitive perspectives. We are interested in understanding how bees evaluate, learn about, and remember flowers. Likewise, we are interested in how the nutritional value of the nectar and pollen plants offer bees structures interactions with pollinators and co-flowering members of plant communities. An interest in understanding how human activities can perturb these interactions drives a parallel line of research, on how sublethal exposure to pesticides can affect bee behavior, sensory systems, and health. We address these questions using a combination of lab-based and field studies, often on bumblebees, at Sierra Nevada and Great Basin field sites.