This clicker case uses plant-pollinator interactions in columbines as a biological scenario to teach students about evolution, reproductive isolation, and angiosperm reproduction. The case is based on an approach to evolution education called tree-thinking that emphasizes the construction, interpretation, and evaluation of phylogenetic trees as an approach to addressing biological and evolutionary questions. It also presents basic concepts of structure-function relationships in flowers and how this influences behavior and effectiveness of different pollinators. Designed for use in a large introductory level class, the case could also be used in smaller classes and in upper-level courses. It is appropriate for use in units on evolution, floral biology, or multispecies interactions.