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Summary Article: Gray, Asa (1810-1888)
From The Hutchinson Dictionary of Scientific Biography

Place: United States of America

Subject: biography, biology

US botanist who was the leading authority on botanical taxonomy in the USA in the 19th century and a pioneer of plant geography. He was also the chief US proponent of Charles Darwin's theory of natural selection.

Gray was born on 18 November 1810 in Sauquoit, New York, and studied medicine at Fairfield Medical School, Connecticut, teaching himself botany in his spare time. After graduating in 1831 he taught science at Bartlett's High School in Utica, New York, until 1834 when he became an assistant to John Torrey, a chemistry professor at the College of Physicians and Surgeons in New York. Also interested in botany, Torrey became a lifelong friend of Gray and the two men collaborated on several botanical projects. In 1835 Gray accepted the post of curator and librarian of the New York Lyceum of Natural History, which gave him more time to devote to botany and provided greater financial security than did his previous position. Gray was made botanist to the US Exploring Expedition in 1836, but he resigned in the following year because of delays in sailing. In 1838 he was appointed a professor at the newly established University of Michigan, but did not commence his duties because, in the same year, he travelled to Europe to acquire books for his library and to study specimens of US plants in European herbaria. On his return to the USA in 1839 he was occupied with writing and organizing the results of his studies. In 1842 Gray accepted the professorship of natural history at Harvard University, on the understanding that he could devote himself to botany. He held this position for 31 years, until he retired in 1873, during which time he made several journeys to Europe, meeting Charles Darwin in 1851, and donated his priceless collection of plants and books to Harvard University on condition that the university housed his collection in a special building; this led to the establishment of the botany department at Harvard University, and the botanical garden and herbarium were later named after him. Gray died on 30 January 1888 in Cambridge, Massachusetts.

Gray was a prolific author, writing more than 360 books, monographs, and papers, but is probably best known for his Manual of the Botany of the Northern United States, from New England to Wisconsin and South to Ohio and Pennsylvania Inclusive (1848), often called Gray's Manual, which was an extremely comprehensive study of North American flora and which also helped to establish systematic botany in the USA. This work went through several editions and is still a standard text in its subject area. Before the publication of Gray's Manual, however, Gray had written several other important works, including the two-volume Flora of North America (1838-43), which he coauthored with Torrey. This work was later expanded, under Gray's direction, and published in 1878 as the first volume of the Synoptical Flora of North America.

In addition to these contributions to botanical taxonomy, Gray also investigated the geographical distribution of plants, notably a comparison of the flora found in Japan, Europe, and northern and eastern North America. This knowledge of plant distribution proved useful to Darwin, who asked Gray to analyse his plant-distribution data in order to provide him with evidence for his theory of natural selection. Darwin also told Gray about his ideas on natural selection as early as 1857, and after the publication of On the Origin of Species (1859) Gray became a leading advocate of Darwin's theory. In his own work, Gray reached conclusions about variations that foreshadowed the work of Gregor Mendel and Hugo de Vries.

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