Callirhytis apicalis (Hymenoptera: Cynipidae)   (Synonym: Andricus apicalis)
Knowland Park, Oakland, Alameda County, California
February 26, 2011

Fresh root gall at the base of Quercus agrifolia (coast live oak) trunk. The gall is attached to the tree and was mostly buried in the soil at the base of the tree. The gall is partially dug out of the soil here.