Timothy A. Dickinson retired from the ROM in 2014 as Senior Curator Emeritus of Botany. He remains an Adjunct Professor in the Department of Ecology and Evolutionary Biology at the University of Toronto, where he was an Associate Professor and taught courses on the plant families of Ontario, field botany, multivariate methods, and ethnobotany. He and his graduate and undergraduate students have studied floral development and, mainly, the evolution and systematics of hawthorns (Crataegus). He is interested in how taxonomists have perceived species in the genus, and in how a better understanding of hawthorn reproductive biology can make for a more robust taxonomy. He has done field work in North America and Jamaica, and is a co-author of 'The ROM field guide to wildflowers of Ontario' and the forthcoming 'ROM field guide to trees of Ontario.'