Organisms adjust to stress by tolerance or avoidance. Buds of deciduous trees that open early in the spring may be damaged by frost, but if they can tolerate frost, they have a longer growing season than deciduous trees that avoid frost by opening their buds later. Native tree species in a location have adapted to recent climatic conditions; however, tree species within families with a northern (Laurasian) origin have adapted more often by tolerance, and tree species within families with a southern (Gondwanan) origin have adapted more often by avoidance. A class project in which students monitor bud opening dates, then test the hypothesis that trees from northern families open their buds earlier, enhances student cooperative learning, awareness of biodiversity, and understanding of evolution. The project works best in temperate regions with high deciduous tree species diversity.

Key words: budburst, deciduous trees, evolution, phenology