Dr. Sharp joined the faculty of the university’s Department of Botany in 1929. He had graduated from Ohio Wesleyan University, where he intended to study for the ministry and where he became a licensed minister at the end of his sophomore year. He earned the master’s degree at Oklahoma, where he developed his interest in mosses. He completed his PhD degree at Ohio State in 1938.
From 1951 until 1961, he served as head of UT’s Botany Department. In 1965 he was designated an Alumni Distinguished Service Professor. From 1958 to 1973 he was associate curator of the UT Herbarium. He retired in 1974 but continued to do research and to teach. He delivered the winter 1975 commencement address at UT.
He was an international authority on bryophyta and liverworts, writing the entries on these subjects in the Encyclopaedia Britannica and Encyclopedia Americana. He served as the first botanist for the Great Smoky Mountains National Park. He coauthored Great Smoky Mountains Wildflowers, served on the editorial committee of the American Journal of Botany (1948–53), and was associate editor for the Bryologist (1938–54), Castanea (1947–49), and the Journal of the Hattori Botanical Laboratory (1961–92). In 1994 the two-volume Moss Flora of Mexico was published, of which he was coauthor, representing the culmination of 50 years of study and research.
He served as president of the American Botanical Society (1965), the American Bryological Society (1935), the American Society of Plant Taxonomists (1961), and the Tennessee Academy of Science (1953). He received a Merit Award from the Botanical Society of America and a Meritorious Teaching Award from the Association of Southeastern Biologists. In 1991 he received the Order of the Rising Sun from the Japanese government for his research into the relationship of the ecosystems of Asia and the Americas, for contributing to the education of Japanese researchers, and for improving academic exchanges between Japan and the United States. In 1992 he was elected a fellow in the Linnean Society.
His intellectual contributions to the life of the university have been recognized by placement of a plaque in his honor on a faculty study.