The career of Paul Deuse started in Belgium in the "Hautes-Fagnes" during the post-war period, but came to its full expansion in Central Africa. Field worker, phytosociologist, trained as an ecologist and a palynologist, teacher, and endowed with a good experience of how to manage a field station and a museum, P. Deuse left Belgium in 1953 for a first three-month tour in Congo. From 1954 to 1956, he worked as temporary researcher for the "Institut pour la Recherche scientifique en Afrique centrale (I.R.S.A.C.)" in Mabali (Congo belge), where he prepared a doctoral thesis on the vegetation of the moorish "esobe" of the lake Tumba. After submitting his thesis at the "Université de Liège" (1957), he was appointed senior research worker at the "I.R.S.A.C." and sent to Astrida (now Butare), in order to make a study of the peat bogs of the Ruanda-Urundi till 1959. After the independance of Congo, he returned to Astrida in July 1960, where he cut down on his research in pollen analysis to assume the responsability of Director of the I.R.S.A.C. Center till the independance of Rwanda. After that, the situation of the research center of Butare became still more difficult until the signature of the "convention belgo-rwandaise" end 1964, which founded the "Institut national pour la Recherche scientifique (I.N.R.S.)" of Rwanda, with P. Deuse as Director. P. Deuse was also part-time assistant lecturer (1961-1965) at the "Centre universitaire de Rumuri" (Bujumbura, Burundi), and senior lecturer (1963-1971) at the "Université nationale du Rwanda" (U.N.R.). A part of the herbarium specimens gathered by P. Deuse before 1955 (406 nos.) are preserved in BR. In 1957 he started a herbarium in Astrida, with duplicates dispatched to Lwiro (LWO). The herbarium of Butare became the "Herbier national du Rwanda" (HNR) in 1965. After the death of P. Deuse, from 1977 onward, the I.N.R.S. was managed by the Government of Rwanda. In 1994, due to the genocide, the research center of Butare was sacked.