Quercus macdonaldii Greene & Kellogg

Quercus macdonaldii has a very restricted distribution to occurrences on Santa Rosa, Santa Catalina and Santa Cruz Islands in the state of California, USA. . Based on molecular genetics analysis, the genus Quercus is estimated to have separated from Castanea about 60 million years ago. Oaks first appear in the fossil record in North America during the Paleogene between 55 to 50 million years b.p. Most interspecific separations occurred within the Quercus species between 22 and three million years ago. During this period, oaks became the most dominant tree type in the Fagaceae family.