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Rosemary H. Ford
Associate Professor
rford2@washcoll.edu
Biology Department
Washington College
Poison Ivy: Taking the Itch Out of the Rash

A longstanding belief that has it roots in Native American folklore is that the crushed leaves of jewelweed (Impatiens capensis) relieve the skin's allergic reaction to the toxin of poison ivy (Toxicodendron radicans). This case was developed for an introductory majors or non-majors biology or plant class. It first examines students' conceptions about the rash of poison ivy, what in the plant causes the rash, and how the body responds to the toxin. Then students in small groups plan an experiment using the scientific method to test the ability of jewelweed to reduce the reaction. Following a comparison of experimental designs from different groups, data from a scientific paper is presented for interpretation and analysis. An important outcome of this case is that students recognize the need for evaluating myths and misconceptions using scientific evidence.