Quercus lobata (valley oak) ( )

Many oak trees host species of wasps, but California's valley oak is one of the best-known and most hospitable of all the oaks. The process begins when a wasp lays an egg on an oak leaf. The plant cells start multiplying at an unusually high rate, forming a kind of protective cocoon called a gall. Eventually the egg hatches into a larva, and the gall, which can get to the size of a baseball, becomes a home to the larva and also gives in something to eat. The larvae emerge as full-grown wasps. One species of wasp causes the valley oak to form small galls that drop off the tree. The galls can jump around for a few days as the wasp inside tries to break free. earning them the name "jumping oak galls". "Wicked Plants, Amy Stewart."