John Maurice Tucker (January 7, 1916, Yamhill County, Oregon – July 5, 2008) was an American botanist, herbarium director, and leading expert on oak taxonomy. At the University of California, Berkeley (UC Berkeley), he graduated in botany in 1940 with a bachelor's degree and in 1950 with a Ph.D. As a graduate student he was the botanist on the University of California's El Salvador Expedition, which lasted from December 1941 to May 1942.His Ph.D dissertation, entitled "Interrelationships within the Quercus dumosa complex", was written under the guidance of Herbert L. Mason, Ledyard Stebbins, and Adriance Foster. The dissertation "dealt with the evolution and relationships of scrub oak (Quercus dumosa) and related species, including hybridization between scrub oak and grey oak (Quercus turb