Gray, Asa (1810โ€“1888), a United States botanist. Gray made important improvements in the system used to classify plants. He trained two generations of botanists and made Harvard University, where he was a professor for 46 years, the leading school for botanical study. Manual of the Botany of the Northern United States (1848) was his most important book. Gray furnished valuable information on plant life that was used in Darwin's Origin of Species (1859). He was one of Darwin's leading supporters in the United States, arguing that the theory of evolution could be reconciled with Christian belief.

Gray was born in Sauquoit, New York. In 1831 he received a degree from the College of Physicians and Surgeons in Fairfield, New York, but never practiced medicine. He was appointed curator of the New York Lyceum of Natural History in 1836 and professor of botany at Harvard in 1842. Gray was president of the American Academy of Arts and Sciences, 1863โ€“73, and was one of the founders of the National Academy of Sciences. He willed his library and extensive herbarium (collection of dried plant specimens) to Harvard. In 1900 he was elected to the Hall of Fame.

Among Gray's many books are Elements of Botany (1836); Structural and Systematical Botany (1879); Natural Science and Religion (1880). With John Torrey he wrote Flora of North America (2 volumes, 1838โ€“43).