The most popular hardwood in California is essentially unavailable in nurseries. California black oak, Quercus kelloggii, provides between a quarter and a third of the hardwood timber harvested in California. One would not know it by its sporadic appearance within mixed forests of the Coastal Ranges. It is much more common in the Sierra Nevada, which might be why no one grows it.
Mature trees can top out at thirty feet with broad canopies if well exposed, or might be more than seventy feet tall and relatively slender if they must compete with other trees. The biggest trees are more than a hundred feet tall. The sculptural trunks are usually less then four feet wide. Trunks of old trees are commonly rotten inside. Gray and smooth young bark gets rough and dark with age.
The distinctively lobed deciduous leaves of California black oak are not much more than four inches long. They can get nearly twice as long on the most vigorous growth, or where shaded. The dark green foliage will slowly turn brown or yellow through autumn, and then defoliate through winter. It can turn a brighter yellow or orange, but then defoliates faster, if the weather gets cool fast.