Danish-American agriculturalist and plant pathologist at the U.S. Department of Agriculture. Born and educated in Copenhagen, Denmark, Herman Theodor Holm (known as Theo) took part in the North Polar Expedition of 1882, working as a botanist and zoologist under Admiral Garda. Over the two years that followed he studied the plants of Greenland and made important contributions to the understanding of polar vegetation. In 1888 Holm moved to the United States. Arriving in New York he immediately applied for citizenship and the same year became an assistant botanist at the U.S. National Museum. Five years later, in 1893, he became a plant pathologist for the U.S. Department of Agriculture and, although he resigned in 1897, continued to produce work for them, including anatomical plant illustrations and the translation of Germanic languages and Latin. At this time he moved to an isolated farm in Maryland, on which he continued his botanical studies uninterrupted, but later his advancing years forced him to take up an appointment as research professor at the Catholic University of America in Washington D.C. Over the years Holm made many important advances in the field, his papers on the Cyperaceae and Poaceae providing valuable information on their taxonomy and distribution, although he also worked on the Commelinaceae and the vegetation of the Colorado Rockies.

Sources:
H.B. Humphrey, 1961, The Makers of North American Botany: 114-115
A.F. Woods, 1990, "Herman Theodor Holm", Science, 77: 183-184.