Merritt Lyndon Fernald (born Oct. 5, 1873, Orono, Maine, U.S.—died Sept. 22, 1950, Cambridge, Mass.) was an American botanist noted for his comprehensive study of the flora of the northeastern United States.
The publication of Fernald’s first paper, at age 17, brought him to the attention of Sereno Watson, then head of the Gray Herbarium at Cambridge, Mass. Watson invited Fernald to work as a helper in the herbarium while he attended the Lawrence Scientific School of Harvard University (B.S., 1897). Fernald remained at Harvard throughout his professional career as instructor, professor, and the curator and director of the Gray Herbarium.
Fernald studied the same floral regions (northeastern United States) as did his famous predecessor, the 19th-century botanist Asa Gray, and he prepared the centennial edition of Gray’s Manual of Botany (1950), one of the best books ever written on the flora of the United States. In 1925 Fernald made a major contribution to glacial geology by refuting the popular theory that nearly all of the northeastern United States and adjacent parts of Canada had been covered by a massive sheet of ice during the Pleistocene epoch. His so-called nunatak (Eskimo word for a hill or peak rising out of a glacier) theory was enunciated in Persistence of Plants in Unglaciated Areas of Boreal America, one of his more than 800 publications. According to Fernald’s theory, there were land areas that escaped glaciation, and they were able to support a large number of species of plants and animals.