Dr. Beth Tonoany, a tropical population ecologist, is studying an unusual tree, Guaiacum sanctum, in the tropical forests of Central America. Interestingly, several local Ticos have told her that they use the tree for medicinal purposes. Students read the case and then answer questions designed to explore the process of screening and testing the medicinal value of plants identified as having potential health benefits. This case can be used in an introductory biology course, an introductory botany course, or any course which encounters ethnobotany as a component, such as a tropical biology course or a plant ecology course.