(1844–1868) was an American botanist, son of the man considered "father of American Public Education".
His mother was one of the famous Peabody Sisters Mary Tyler Peabody Mann.
Mentored in botany by Henry David Thoreau, whom he accompanied on an expedition to Minnesota, Mann took classes in zoology with Louis Agassiz and assisted William Tufts Brigham botanize the Hawaiian Islands.
Mann was to have headed the botanical garden at Harvard, but died of tuberculosis at age twenty-four.
His own herbarium was purchased by Cornell University and became the basis of that university's collection.
He is credited with the discovery of more than 100 species.