Michael A. Dirr is a renowned horticulturist and a professor emeritus of horticulture at the University of Georgia. He is widely recognized as one of the leading experts on woody plants in North America. Dirr has authored several definitive books on the subject, including the popular "Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation and Uses,” which is widely used as a textbook and reference guide by students, horticulturists, and landscape professionals. His work is known for combining rigorous science with practical experience, and his contributions to horticulture include both academic research and plant breeding, resulting in the introduction of numerous new plant varieties to the ornamental plant market. Dirr's passion for plants and engaging writing style have made him a respected and influential figure in the field of plant sciences.