Lucien Marcus Underwood was born on October 26, 1853, in New Woodstock, Madison, New York.

He was an American botanist, mycologist, and educator. He graduated from Syracuse University (M.Sc., 1878; Ph.D., 1879). In the 1880s and 1890s, Underwood taught geology, botany, biology, and natural science at several colleges and universities, e.g., Illinois Wesleyan University, Syracuse University (1883; 1887-1890), De Pauw University (1890-1895), Auburn University, and Columbia University (1896-1907). In 1892, Underwood served on the Committee on Nomenclature of the American Association for the Advancement of Science. He joined the staff of the New York Botanical Garden (NYBG) in 1896. He participated in botanical expeditions to Puerto Rico, Cuba, Jamaica, and the Rocky Mountains and was elected to the NYBG Board of Scientific Directors and served as its chairman (1901-1907). He contributed a section on Pteridophyta to the Britton & Brown Illustrated Flora, was editor of the Bulletin of the Torrey Botanical Club and assisted in the founding of the Botanical Society of America. Underwood published numerous papers in botanical journals and was the author of “Our Native Ferns and How to Study Them” (1881) and “Descriptive Catalogue of North American Hepaticae” (1884).

In 1881, he married Marie Annette Spurr (1854–). After losing large amounts of money on Wall Street, he committed suicide on November 16, 1907, in Redding, Fairfield, Connecticut.