Swedish lichenologist. Theodor M. Fries was born in Femsjö, Småland, and his father was the renowned mycologist and professor at Uppsala University, Elius Magnus Fries. Studying under his father from 1851, Theodor Fries would also teach at the university from 1862, and was made a professor of botany and practical economy in 1877. Interested in lichens from the first, he produced an essay entitled De Stereocaulis et Pilophoris commentatio for his doctoral degree which he received in 1857. The following year Fries published monographs for each of these taxa. Primarily interested in his local lichen flora, he conducted three field trips to northern-most Scandinavia (Finnmark in Norway) in 1857, 1864 and 1901, as well as to Spitsbergen in 1868 and Greenland in 1871. With his findings Fries published Lichenes Arctoi, a seminal work on arctic lichen. An even bigger publication, though, was yet to come. His Lichenographia scandinavica was published in 1871 and 1874 and covered much of the Scandinavian lichen flora, although he was unable to complete the third and final part.

Fries adopted a classification system which was not in accordance with that of the Finnish lichenologist and world expert at the time, William Nylander. Although Fries received much criticism for this, his system is now considered superior. Serving as chancellor of the university between 1893 and 1899, he published several text books for his students and was a talented teacher. Leaving the university in 1899 he concentrated on writing a two volume biography of Linnaeus in later life. Fries married Gustava Katarina Anjou and two of their nine children went on to become botanists.

Sources:
R.E. Fries, 1950, A Short History of Botany in Sweden: 53-54
P.M. Jørgensen, 2001, "Th. M. Fries (1832-1913), A Grand Scandinavian Lichenologist", Bryologist, 104(4): 537-542.