Knud Jessen


Knud Jessen was a Danish botanist and quaternary geologist.
He was state geologist 1917–1931. In 1931, he succeeded C.H. Ostenfeld as professor of botany at the University of Copenhagen and director of the Copenhagen Botanical Garden, a position he held until his retirement in 1955. His scientific works mainly concern vegetation history during the Eemian interglacial, the late glacial period of the Wisconsin glaciation and in the Holocene investigated using pollen analysis.
Jessen had come into contact with the Irish naturalist Robert Lloyd Praeger and made field-work on the quaternary geology of Ireland during 1934-1935. Together with his assistant, Frank Mitchell, he was able to describe both the post-glacial vegetation development of Ireland and that of the Eemian interglacial, with the presence in Ireland of such plants as Rhododendron ponticum, Abies alba, Erica scoparia and Buxus sempervirens.
Jessen was acknowledged by honorary doctorates at the University of Cambridge and University of Dublin. He was a member of the Royal Danish Academy of Sciences and Letters and served on the board of directors of the Carlsberg Foundation. Jessen also lived in the Botanical Gardens in his later life.

Personal Life

Jessen married Ingrid Holm, and had four children, including Jørgen Holm Jessen, Niels Jessen, and Poul Holm Jessen, who was a successful chemist who founded and ran the plastics company Scandiplex.

Selected scientific works