Quercus Garryana - Growth Characteristics

Growth Characteristics

It is a drought-tolerant tree, typically of medium height, growing slowly to around 20m (occasionally as high as 30m) or as a shrub to 3–5 m tall. It has the characteristic oval profile of other oaks when solitary, but is also known to grow in groves close enough together that crowns may form a canopy. The leaves are deciduous, 5–15 cm long and 2–8 cm broad, with 3-7 deep lobes on each side. The flowers are catkins, the fruit a small acorn 2–3 cm (rarely 4 cm) long and 1.5–2 cm broad, with shallow, scaly cups.

The Oregon white oak is commonly found in the Willamette Valley hosting the mistletoe Phoradendron flavescens. It is also commonly found hosting galls created by wasps in the family Cynipidae. 'Oak apples', green or yellow ball of up to 5 cm in size, are the most spectacular. They are attached to the undersides of leaves. One common species responsible for these galls is Cynips maculipennis. Other species create galls on stems and leaves. Shapes vary from spheres to mushroom-shaped to pencil-shaped.

In British Columbia, the Garry oak can be infested by three nonnative insects: the jumping gall wasp Neuroterus saltatorius, the oak leaf phylloxeran, and the gypsy moth.

While the invasive plant disease commonly called Sudden Oak Death attacks other Pacific Coast native oaks, it has not yet been found on the Garry oak. Most oak hosts of this disease are in the red oak group, while Garry oak is in the white oak group.