The Oregon white oak (Quercus garryana) and California black oak (Quercus kelloggii) are two of the more common oaks in Northeastern California. Although there are differences in the leaves, bark and acorns, these two oaks often are easy to confuse, especially since they will hybridize. In the spring as these two oaks begin to leaf out, they present, for a brief time, a strikingly different appearance.
Both the California black and Oregon white oaks are monoecious, that is the male and female flowers are borne in separate inflorescences on the same tree. Flowering at the same time the leaves first appear, the inconspicuous male flowers are on hanging catkins while the female flowers are equally inconspicuous. The leaves of the California black oak already have the “bristles” at the tip of each leaf lobe while the Oregon white oak lobes assume the rounded shape of the mature leaf.
The emergent spring foliage of California black oaks is bright pink, reddish or cinnamon for a brief period. The tender Oregon white oak leaves are green. From a distance the two trees can easily be distinguished in the spring, one is green and the other a red color. As the California black oak leaves mature they turn green and the two trees appear similar in color. In the photographs the bark of the California black oak also appears much darker than the bark of the Oregon white oak, another identification trait.
Another post comparing the Oregon white oak and the California black oak can be found here: “California Black and Oregon White Oaks”.
These oak trees were photographed along the Lower Hat Creek (Shasta County CA).