Trelease bridged the era of Asa Gray, whom he know, and the twentieth century to become an internationally known botanist, teacher, and administrator. He was the son of Mary Gandall and Samuel Ritter Trelease, of Dutch and Cornish ancestry. After attending schools in Branford, Connecticut, and Brooklyn, New York, he entered Cornell University, where he studied under the botanist A.N. Prentiss and the entomologist John H. Comstock. While still an undergraduate he published four papers on pollination in American Naturalist and the Bulletin of the Torrey Botanical Club, and made field studies for the United States government on cotton insects in Alabama. Following his graduation (B.S., 1880), he entered Harvard to study fungi under William G. Farlow. During his Harvard year he came under the influence of Gray, Sereno Watson, George L. Goodale, and Samuel H. Scudder.
Beginning in 1881 Trelease taught systematic botany, horticulture, forestry, and economic entomology at the University of Wisconsin. To these courses he added bacteriology, the first time it was offered in the United States. In 1884 he was awarded the science doctorate at Harvard; his thesis concerned the zoogloeae. George Engelmann and Gray urged Henry Shaw to appoint Trelease the head of the newly established Missouri Botanical Garden in St. Louis, popularly known as Shaw’s Gardens, to be patterned after the Royal Botanic Gardens at Kew. In twenty years Trelease brought together a garden of 12,000 species under cultivation, a notable library of some 70,000 books (including the E. L. Strutevant pre-Linnaean collection), and a herbarium of 700,000 specimens.
Following his resignation in 1912 and a year in Europe. Trelease assumed the headship of the department of botany at the University of Illinois, where he remained until his retirement in 1926. Among his 300 published papers and books were monographs on the genus Agave, mistletoes, and oaks, and an unfinished work on Piperaceae begun when he was seventy-five years old. Trelease described more than 2,500 species and varieties of plants. Addicted to bibliographic thoroughness, he was able to provide in his work a base for modern research involving supplemental techniques. Nonetheless, Trelease found time to serve as president of the leading organizations of his profession.
I. Original Works. For a bibliography of Trelease’s writings see Kunkel (below). Trelease’s noteworthy writings include Botanical Works of the Late George Engelmann (Cambridge, 1887), with Asa Gray; articles for L. H. Bailey’s Cyclopedia of American Horticulture (New York, 1990–1902); Agave in the West Indies (Washington. D.C., 1913); The Genus Phoradendron (Urbana, Illinois, 1916); and the American Oaks (Washington, D.C., 1924).
The Piperaceae of Northern South America (Urbana, 1950) was completed by T. G. Yuncker. Trelease’s papers on Mexican botany are listed with annotations in Ida K. Langman. A Selected Guide to the Literature on the Flowering Plants of Mexico (Philadelphia, 1964).
Four scrapbooks of letters, clippings, and memorabilia are preserved at the Missouri Botanical Garden.
II. Secondary Literature. The fullest sketch is L.O. Kunkel, in Biographical Memoirs. National Academy of Sciences, 35 (1961), 307–332, with a portrait and bibliography of his writings by T. G. Yuncker for the years 1879–1950. See also L. H. Bailey in Yearbook. American Philosophical Society (1945), 420–425; and J. M. Greenman, in Missouri Botanical Garden Bulletin, 33 (1945), 71–72. Personal tributes are J. Christian Bay. William Trelease. 1857–1945. Personal Reminiscences (Chicago. 1945); and L. H. Pammel, Prominent Men I Have Met , III (Ames, Iowa, 1927), both privately printed.