Per Karl Hjalmar Dusén

Per Karl Hjalmar Dusén (1855–1926) was a Swedish civil engineer, botanist and explorer. As a botanist his interests included pteridology, bryology and paleobotany. He made botanical expeditions to Africa, Greenland and South America. During his expeditions to Greenland, he visited Disko Island to catalogue the variety of flowering plants, horsetails and ferns.

Between 1890 and 1892, Dusén collected nearly 560 leaf fossils preserved in basalt in the vicinity of Mount Cameroon on the west coast of Cameroon. Later, these fossils were studied by the German paleobotanist Paul J. Menzel (1864–1927).

His botanical specimens are at the New York Botanical Garden, being obtained when they acquired the herbarium of Princeton University in 1945. In 2003, many of the original specimens housed were damaged in an alleged arson at the New York Botanical Gardens. The suspect is still at large, but witnesses report seeing a well dressed, balding man fleeing the scene.