American bryologist. Born in Minneapolis, Minnesota, Robert Statham Williams was an ardent naturalist from boyhood with a special interest in birds, insects, and plants. At the age of 20, he moved to Montana where he made a living for nearly two decades as a miner, businessman, explorer, and, for a short time, rider for the Pony Express. As a homesteader, he built the first cabin in what became the city of Great Falls. He also received a grant from Columbia College, New York, to collect bryophytes for Elizabeth Britton. In 1898 he joined the Klondike Gold Rush, travelling the Chilkoot Trail to Yukon Territory. He made a small fortune in business rather than gold prospecting, and was the first resident naturalist to make botanical collections in the Klondike.

In 1899, Williams arrived with his plant collections at the newly created New York Botanical Garden, then under the direction of Nathaniel Britton, husband of Elizabeth Britton, with the intention of devoting the rest of his life to science. He was given the title of Museum Aide and, after completing a report on his moss collections from Alaska and the Yukon, was sent on several long collecting trips. In fact, he was the first scientist from the Garden to be sent to South America.

In 1901, H.H. Rusby, curator of the Economic Collections at the Garden, arranged for him to act as botanist on a journey to the Amazon Basin of eastern Bolivia with an exploration party for the Bolivia Company, an English firm with interests in minerals and rubber production. He was to produce a report for the company on the economic features of the plants he collected and observed, and to collect seeds and living plants for the Garden's horticultural collections whenever the opportunity presented itself on the journey across Bolivia and Peru. Following his return to New York in 1902, he published brief accounts of the expedition and two papers on his collections of mosses, including descriptions of novelties. He handed the rest of the material, more than 200 species of vascular plants, to Rusby for analysis.

From 1903 to 1905, he collected in the Philippines, mainly on Luzon and Mindanao. The bryological material from this expedition forms the basis of his authoritative work on Philippine mosses, which he published in 1914. His expedition to Panama in 1908 proved to be his last collecting trip. It is important to bear in mind that Williams repeated his numbering series on each expedition; therefore, when referring to his plant specimens, collection number and country should always be associated. Williams also maintained a lifelong interest in birds, and decorated the room in the Bronx where he lived with mounted skins of exotic birds collected on his travels and with native birds from nearby Bronx Park. Many of these specimens are now in the collection of the American Museum of Natural History.

In 1909 the New York Botanical Garden acquired the William Mitten Herbarium, a superb collection of mosses from all parts of the world, containing hundreds of type specimens. With this collection as a reference, Williams, who advanced to assistant curator in 1906 and to administrative assistant in 1910, was able to establish himself as an authority on exotic mosses. His research was concerned with floristics, not questions of phylogeny and relationship. He worked on collections from his own expeditions and those of others, prepared monographic revisions, and was a frequent contributor to The Bryologist, as well as being an honorary life member of the Torrey Botanical Club and a president of the Sullivant Moss Society (1924-1930). In 1932 he was made research assistant in bryology. However, after losing his life savings in the Depression, he was consumed by money worries, which brought on a serious illness in 1936, after which his enthusiasm for bryology gradually waned. He never formally retired but took a permanent leave of absence and spent his last years living with a sister in their childhood home in Minneapolis. A genus of flowering plants, Williamsia Merr., and two genera of mosses, Williamsia Broth. and Williamsiella Britton, as well as many species of flowering plants from the Yukon, Bolivia, the Philippines, and Panama bear his name.

Sources:
J.H. Barnhart, 1945, "Robert S. Williams", Journal of the New York Botanical Garden, 46: 146-147
L. Dorr, 1991, "The Vascular Plants of R.S. Williams from Bolivia and Peru (1901-1902)", Brittonia, 43(4): 211-239
W.C. Steere, 1945, "Robert Statham Williams", The Bryologist, 48: 93.