Tree Blog

Davis

This is what appears to be a native California twig gall, growing on the herein-purported hybrid Q. robur x douglasii. Twig and leaf galls are created, typically by wasps who predate common oak pest insects. They are considered natural symbionts of the native oaks. There can be little doubt that this tree contains native oak genetics. But, interestingly, if the hybrid parentage proves accurate, here we are seeing native insects making full and familiar use of an oak with a substantial portion of its genetics originating far from California. This observation, again, if substantiated, suggests that commonly understood notions of what makes an organism "native" are perhaps worth rethinking, especially in light of the currently rapid pace of climate change.

Dave Muffly