He was appointed professor of botany at the Norwegian College of Agriculture from 1965. His research interests centered on Arctic plants and lichen, plant geography and ecology. He was also a politician for the Labour Party, where he was a board member from 1965 to 1977.
After fleeing to Sweden and later to the United Kingdom, he served with the Norwegian High Command in London.
During the German occupation of Norway he took part in resistance work, and was a member of the clandestine intelligence organization XU.