California black oak
Native to the hills not far from campus, black oak is a deciduous tree with deeply lobed leaves (usually seven lobes) and a number of bristles on each lobe where the veins terminate. The leaf shape is similar to that of Quercus coccinea, but the color is a deeper green, glossy on top and lighter beneath. The acorn is about 1½ inches long, about half enclosed in the scaly cup. California black oak accounts for about one-fifth of all hardwoods in California.
To see fine examples, sign up for a tour of Jasper Ridge Biological Preserve. Six young trees, deep hybrids with Q. agrifolia, are on Bonair Siding at the edge of the Maples Pavilion parking lot. Q. agrifolia introgression into black oak appears to help stave off leaf diseases.
Illustrations: Jasper Ridge plant photo archive.
About this Entry: The main text of this entry is from the book Trees of Stanford and Environs, by Ronald Bracewell, published 2005. Q. agrifolia hybrid information for the Bonair trees added Oct 2017 (Dave Muffly, SP).