As teacher, he was an instructor in botany (1900–1910), associate professor of botany (1915–1926), professor of botany (1926–1932) and Arnold professor of botany (1932–1935).
In seiner lehrenden Tätigkeit war er Instructor in Botany (1900–1910), Associate Professor of Botany (1915–1926), Professor of Botany (1926–1932) und Arnold Professor of Botany (1932–1935).