Clements is best known for his theory of community development or plant succession. He claimed that a plant community underwent a predictable series of developmental stages that was comparable to the development of an organism. The final stage or climax community was determined by the climatic conditions of a geographic area. For Clements, the plant community was, in fact, a “complex organism” with a physiology that could be studied with the same precision as an organism in the laboratory. These organismal ideas were both influential and controversial during Clements’s lifetime. They focused considerable attention on plant succession as a major research area for American ecologists during the early decades of the twentieth century, when the discipline was becoming established. Although widely rejected by later ecologists, Clements’s organicism and physiological perspective persisted in attenuated form even after World War