Both of these pots of clover plants have been growing for 30 days, but one looks healthier than the other! The clover plants in the top picture (A) were given normal water. The clover plants in the lower picture (B) were given acidic water (pH=2.0) for the latter 20 days. When air pollution causes acid rain, plants that rely on rain water to live and grow are endangered.
Greg Anderson, Bates College, Department of Biology