Summary Parasitism is a successful life strategy that has evolved in all known kingdoms of life. Parasitic plants are diverse and found throughout the world. Familiar examples of parasitic plants include mistletoes, which attach to tree and shrub branches, and wildflowers such as Indian paintbrush (Castilleja spp). Lesser known parasitic plants include some truly remarkable species, some of which challenge the typical definition of a plant because they lack roots, leaves, or even the ability to photosynthesize. In this Teaching Tool, we explore the biology and evolution Of parasitic plants, and their impact on agriculture. In the last portion of the Teaching Tool, we discuss the molecular evolution of a parasitic adaptation at a level intended for advanced students. Posted April 30, 2017.