From 1935 until 1961, Degelius was a
docent (an academic appointment below the rank of Professor) in botany at Uppsala University. He worked under the supervision of Professor
Gustaf Einar Du Rietz, along with
Sten Ahlner,
Torsten Hasselrot, and
Rolf Santesson – all of whom became notable lichenologists. During this time, Degelius travelled (often with Ahlner and Hasselrot, at least initially) to many locations in
Scandinavia to collect lichens. In 1939, he visited the United States and subsequently published two papers on the lichens of
Maine, and the lichens of the
Great Smoky Mountains of
Tennessee, both of which were highly regarded by later researchers. He has been credited for having introduced the lichen terms and in a 1945 publication, referring to previously undescribed asexual
propagules he had observed on the lichen
Lempholemma cladodes. Degelius returned to Gothenburg in 1955 to take a position at the
Gothenburg Botanical Garden. Degelius also lectured about the subject of systematic botany at the
University of Gothenburg until his retirement in 1969. After his retirement, Degelius travelled the world, visiting exotic locations on several continents to continue his lichen studies. He collected his last lichen in Estonia in 1991. His private
herbarium, which had accumulated more than 50,000 specimens, is now housed at Uppsala University. He described 124 new
taxa (mostly species), and published about 130 scientific papers. Although most of these were about lichens, he also published papers on
phanerogams, mosses, and non-lichenized fungi. Degelius was also interested in studies on
floristics, publishing
floras for several Nordic locales as well as other more distant locations. Lichen biology and ecology was another interest, and he published research on the competition between
rock-dwelling lichens, discovered a type of
diaspore called a lichenized hormocyst, and studied the
ecological succession of lichens growing on
Fraxinus twigs. Degelius is best known for his work on the genus
Collema. His first publication on this group appeared in 1936. In 1954 he published a
monograph of the European species, and then 20 years later, a world monograph. Degelius won a
Linnean Medal for this work. ==Personal life==