Oregon white oak, also known as Garry oak or Oregon oak, is a drought tolerant tree that grows slowly to around 65-80 ft. The leaves are deciduous, 3-6″ long and 2-5″ broad, with 7-9 deep lobes on each side. The flowers are catkins, the fruit a small acorn about 1″ long, with shallow, scaly cups.
In the Willamette Valley, oaks are common habitat for mistletoe Phoradendron flavescens and gall wasps Cynips maculipennis. Gall wasps have a unique survival strategy: they secrete chemicals that interfere with the oak’s normal growth hormones, which causes small, abnormal growths on the underside of leaves wherever eggs are laid. The gall grows around the developing gall wasp larvae and provides them food and shelter. Galls normally do not harm oaks, though heavy infestations can stress trees. The Garry oak is also the only known food for Bucculatrix zophopasta caterpillars.
History and uses
Before the European settlers came into the Willamette Valley, the oaks were mostly open-grown individual trees due to the burning practices of the native Calapuya people. Now, wildfires are almost unknown in the Willamette Valley. Since the settlers did not continue this practice, the intervening land was soon covered with seedling oaks (called “scrub oaks” by the settlers) which grew vertically and formed a closed canopy. Remnants of the old open-grown oaks are still found in these closed oak stands.
Although the wood has a beautiful grain, it is difficult to season without warping and therefore the Garry Oak has not historically been regarded as having any commercial value and is frequently destroyed as land is cleared for development. However, Garry Oaks and their ecosystems are the focus of conservation efforts, including in communities such as Oak Bay, British Columbia, which is named after the tree, and Corvallis, Oregon. Moreover, recently the wood, which is similar to that of other white oaks, has been used experimentally in Oregon for creating casks in which to age wine.
Oregon white oak ranges from southern California to extreme southwestern British Columbia, particularly southeastern Vancouver Island and the adjacent Gulf Islands. It grows from sea level to 210 m altitude in the northern part of its range, and at 300-1800 m in the south of the range in California. The tree is named after Nicholas Garry, deputy governor of the Hudson’s Bay Company, 1822-35.
- Light Requirements: Full Sun
- Water Requirements: Dry, Moist
- Ease of Growing: Moderate
- Growth Rate: Slow
- Spreads: No
- Wildlife Support: Pest-eating Insects, Birds or Mammals
- Edible: No
- Mature Height: 25-70ft
- Mature Width: 30-60ft