Take galls, for example. Galls are deformities found on the leaves, stems and flowers of trees, shrubs and other plants. Plant galls come in a fascinating variety of strange forms, textures and colors. . Some galls sport thick growths of fuzz, hair or spines. Gall formation is an equally bizarre biological puzzle.
Galls result from an intricate interaction between two living organisms.
Gall-makers, the organisms that initiate the process, are tiny, highly specialized wasps, flies, mites, aphids or microbes. Their attack on a host plant unleashes a unique response. The plant abruptly changes the course of normal growth and modifies growing tissue into a special swelling that surrounds the tiny insects and mites. The mystery of gall formation was not understood until recent times, even though galls have been written about since the days of the Roman Empire. Thousands of species of insects and mites produce galls on hundreds of species of plants.