Gleasonian UK /ɡliːˈsəʊ.ni.ən/US /ɡliˈsoʊ.ni.ən/ adjective1 •Of or relating to Henry A. Gleason (botanist) (1882–1975), American ecologist, botanist, and taxonomist, known for his endorsement of the individualistic or open community concept of ecological succession, and his opposition to Frederic Clements's concept of the climax state of an ecosystem. formsmore Gleasonian · most Gleasonian