The Oregon white oak (Quercus garryana), also known as Garry oak, has a range from northern California to British Columbia. They grow into medium-size trees, 20m, occasionally as high as 25m, and can have the characteristic oval profile of other oaks when solitary, but are also known to grow in groves close enough together that their crowns form a conopy.

The Oregon white oak is commonly found in the Willamette Valley hosting the American mistletoe (Phoradendron flavescens). It is also commonly found hosting a green or yellow ball of up to two inches in size, attached to the underside of some of the leaves. This abnormal growth -- a gall -- is formed by the oak around a colony of wormlike larvae belonging to one of several species of tiny wasps. The most common species responsible for these galls is Cynips maculipennis.