Dr. Hesler earned the bachelor’s degree from Wabash College in 1911 and the PhD from Cornell in 1914. He joined the UT faculty in 1919 as professor of botany. He served as head of the Botany Department and became dean of the College of Liberal Arts (now Arts and Sciences) in 1934. In 1936, he declined to become dean of the university (a position roughly equivalent to executive vice president), preferring to remain dean of liberal arts.
Captain of his track team and a four-year letterman at Wabash College, participating in the 120 high hurdles and the high and broad jumps, he became a semipro baseball pitcher and played in western New York in the summers of 1912 and 1913 and in Puerto Rico while working at the Federal Agricultural Experiment Station during World War I. He vigorously promoted track and field events at UT and served for many years as head timer in the Southeast. In the spring of 1921, he served as track coach, in addition to his professorial responsibilities. He was a member of the Athletics Council from 1924 until his retirement in 1958.
He achieved an international reputation in the field of botany. He was the author of eleven books about mushrooms and other fungi (six of them published after his UT retirement), and more than one hundred articles in scientific journals. His Mushrooms of the Great Smokies, published by UT Press in 1960, was awarded two prizes for excellence: the Silver Pen Award for clarity of writing and an award from the Southern Library Association. He was a member of many scientific and scholastic societies, including Sigma Xi, Phi Beta Kappa, Phi Kappa Phi, Alpha Zeta, the American Association for the Advancement of Science, the Mycological Society of America, and the Tennessee Academy of Science. He was a major force in the Scarabbean Society, and promoted leadership and academic excellence. The Hesler Biology Building was named for him in 1958 at his retirement. The Hesler Award also is named in his honor.