Plants are “at war” all around us-engaging in allelopathy. Allelopathy is a poorly-understood process in which certain plants release chemicals that inhibit the growth of other plants. One of the best known examples is the black walnut, Juglans nigra, which secretes a chemical called juglone, a toxic substance to many plant species. Tomatoes and many other vegetables suffer “walnut wilt” and die if their roots come in contact with the roots of walnut trees.Students germinate two types of seeds to determine if any allelopathy exists between the two species. The results are dramatic and serve as a stimulus for further study of allelopathic interactions. All seeds and germinating materials are provided.Enough materials are supplied for 30 students working in pairs.