Education
Educated at the University of Iowa and Michigan Technological University he graduated Bachelor 1969 and taught at Michigan Technological University and Michigan State University (1975-1983), and at the Missouri Botanical Garden, Saint Louis, Missouri since 1983, where he has been Assistant Curator since April 2005.
Career
He has conducted botanical expeditions in both Africa (Cameroons, Republic of Congo, Ethiopia, Kenya, Madagascar, Tanzania and Uganda) and the Americas (Costa Rica, Guatemala and Mexico). Gereau has specialised in the Floristics and phytogeography of eastern Africa, he is also engaged in collaborative studies between ethnobotany and archeology. Gereau is noted for his contributions to the study of the Ancistrocladaceae, Mimosaceae and Sapindales of Africa.