Quercus kelloggii California black oak

Quercus kelloggii, northernmost of the six on Bonair Siding. Sairus Patel, 8 Oct 2017

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.

Quercus kelloggii leaves, second most northern of the six on Bonair Siding. Sairus Patel, 8 Oct 2017

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.

Quercus kelloggii leaf and acorn. From: Howard E. McMinn & Evelyn Maino, An Illustrated Manual of Pacific Coast Trees

Illustrations: Jasper Ridge plant photo archive.