January 6, 1906–January 19, 2000

BY VASSILIKI BETTY SMOCOVITIS AND FRANCISCO J. AYALA

GEORGE LEDYARD STEBBINS’S most important scientific contribution was the publication in 1950 of Variation and Evolution in Plants, the last of a quartet of classic books that in the second quarter of the twentieth century set forth what became known as the synthetic theory of evolution or the modem synthesis. The other books are Theodosius Dobzhansky’s Genetics and the Origin of Species (Dobzhansky, 1937), Ernst Mayr’s Systematics and the Origin of Species (Mayr, 1942), and George Gaylord Simpson’s Tempo and Mode in Evolution (Simpson, 1944). The pervading conceit of these books is the molding of Darwin’s evolution by natural selection within the framework of rapidly advancing genetic and biological knowledge. Variation and Evolution in Plants distinctively extends the scope of the other books to the world of plants, as explicitly set in the book’s title. Dobzhansky’s perspective had been that of the geneticist and he set the tone for the others, Mayr’s that of the zoologist and systematist, and Simpson’s that of the paleontologist. All four books were outcomes of the famed Jesup Lectures at Columbia University. Plants, with their unique genetic, physiological, and evolutionary features, had been all but left completely out of the synthesis until that point. In 1941 the eminent botanist Edgar Anderson had been invited to