Park S. Nobel is the Distinguished Professor of Biology Emeritus in the Department of Ecology and Evolutionary Biology at the University of California, Los Angeles. His early career focused on cell physiology, especially chloroplasts, and his first book was entitled Plant Cell Physiology: A Physicochemical Approach (W.H. Freeman, 1970).He eventually shifted toward plant physiological ecology and has written six books on the subject that have been cited extensively. Besides writing these texts, he has published six books on agaves and cacti. He has also authored nearly 400 scientific research articles and reviews.Dr. Nobel has developed original equations for the air boundary layers surrounding cylinders and spheres and has championed the importance of the mesophyll surface area per unit leaf area, Ames/A. Other research topics have included the importance of shallow root distribution for taking advantage of light desert rainfalls and the influences of an air gap developing around roots during drought on root-soil water movement.