Dirr, Michael A.: - Back Cover Copy After earning a Ph.D in Plant Physiology from the University of Massachusetts Amherst, Michael Dirr became an Assistant Professor of Ornamental Horticulture at the University of Illinois, Urbana. He went on to become a Mercer Fellow at the Arnold Arboretum of Harvard University, and, in 1979, the Director of the University of Georgia Botanical Garden. In later years he taught at the University of Georgia. Dirr's Georgia Plant Introduction Program has introduced over 40 new cultivars into the nursery trades. After retiring from his professorship at the University of Georgia, Dirr has become more active in botanical research and new plant development.