Hybrid Oak brightens winter forests

Dec 15, 2011

The oak woodlands of the UC Hopland Research & Extension Center turn to shades of drab colors for the winter.  However, occasionally one can spot a lone tree with yellow-golden leaves.  Many old-timers referred to this tree as a "golden oak".   Scientifically, what they are referring to is the Oracle Oak.   For decades most botanists considered this oak tree to be a hybrid of the Black Oak (Quercus kelloggii) and the Interior Live Oak (Quercus wislizenii).

Some botanist now refer to the tree as a separate species ... Quercus morehus. Any way that you look at it, the trees always occur in areas where there are lots of one of the parent trees and not many of the other parent trees.  The leaf looks like a cross between the big sharp-pointed, but lobed, black oak leaf and the small, sometimes serrated live oak leaf.  Of course the black oak is deciduous and the live oak is evergreen, so the Oracle Oak can't quite make its mind up and retains most leaves far into the winter.  Many of these leaves turn bright yellow in color ...hence the layman's name of "golden oak".

Quercus morehus was a Latin name given to a singular tree at the northerly end of Lagoon Valley, Solano County, by Dr. Albert Kellogg during the 1800's.  Dr. Kellogg was one of the founders of the California Academy of Sciences in 1853.

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By Robert J Keiffer
Author - Center Superintendent