Léon Camille Marius Croizat (July 16, 1894 – November 30, 1982) was a French-Italian scholar and botanist who developed an orthogenetic synthesis of evolution of biological form over space, in time, which he called panbiogeography. Life Croizat was born in Torino, Italy to Vittorio Croizat (aka Victor Croizat) and Maria (Marie) Chaley, who had emigrated to Turin from Chambéry, France. In spite of his great aptitude for the natural sciences, Leon studied and received a degree in law from the University of Turin. Croizat and his family (wife Lucia and two children) emigrated to the United States in 1924; an avid artist, Leon worked selling his artwork for several years, but could not succeed economically as a working artist after the stock market crash of 1929. During the 1930s, Croizat found a job identifying plants as part of a topographic inventory performed in the public parks of New York City. During his visits to the Bronx Botanical Gardens, he became acquainted with Dr. E. D. Merrill. When Merrill was appointed director of the Arnold Arboretum of Harvard University in 1936, he hired Leon as a technical assistant (in 1937.) Croizat became a prolific student and publisher, studying important aspects of the distribution and evolution of biological species. It was during this time that he began to formulate a novel current of thought in evolutionary theory, opposed in some respects to Darwinism, on the evolution and dispersal of biota over space, through time. In 1947, Croizat moved to Venezuela after receiving an invitation from botanist Henri Pittier. Croizat then obtained a position in the Faculty of the Department of Agronomy at the Central University of Venezuela. In 1951 he was promoted and was awarded the title of Professor of Botany and Ecology at the University of the Andes, Venezuela. Between 1951 and 1952 he participated in the Franco-Venezuelan expedition to discover the sources of the Orinoco river. Croizat served with the expedition as a botanist with professor Jose Maria Cruxent. During his time in Venezuela Croizat divorced his first wife. Croizat was later remarried to his second wife Catalina Krishaber, a Hungarian immigrant. In 1953 Croizat gave up all official academic positions to work full-time researching biology. Croizat and his wife Catalina lived in Caracas until 1976. In 1976 they took over as first directors of the “Jardin Botanico Xerofito” in Coro, a city approximately 400 kilometers West of Caracas. Jardin