Garry oak, Quercus garryana, is a beautiful, white oak tree native to the Pacific Coast of North America. They can grow to be quite large, with mushroom-shaped canopies of green leaves and sturdy trunks wrapped in bark that is white to grayish in color and distinctly furrowed. You will find them growing from Vancouver Island, British Columbia to Southern California. Garry oak is the only native oak in Washington and British Columbia, and the principle native oak of Oregon.
Garry oak ecosystems provide an incredibly rich habitat for wildlife. Intact Garry oak ecosystems with Garry oak trees and associated understory ecosystem plants have become rare, and in some locations are critically imperiled and at risk of extinction.
Many of the Garry oak ecosystems we see today are of Native American origin, who since time immemorial have tended Garry oak ecosystems and encouraged their growth. These special trees and their ecosystems are worth planting and preserving for future generations.
A Garry oak tree in summer.
Artists’ depiction of Native Americans harvesting Garry oak acorns, camas, and chocolate lily in a Garry oak meadow.
Garry oak range map from the US Forest Service.
Where do Garry oaks grow?
Garry oaks grow from southwest British Columbia to the central coastal area of California. Garry oaks can grow in a variety of soil conditions from dry, rocky slopes or bluffs, to deep-soil meadows.
Old growth Garry oaks in Smith Park – Oak Harbor, WA.
What are the names of this tree?
Like many plant species, this tree goes by many names of a range of origins including tribal, common english, and latin scientific. The Garry oak’s latin scientific name, Quercus garryana, was bestowed by Botanist David Douglas in the early 1800’s to honor of his friend, Nicholas Garry, an officer in the Hudson Bay Trading Company.
The tree has several common English-language names including Garry oak, Oregon oak, Oregon white oak, and white oak. We have found that it is more typical to hear this species commonly referred to as “Garry oak” in British Columbia and Washington, and “Oregon oak” or “Oregon white oak” in Oregon and California.
The tree also has its own names in the languages of Native Americans.
Portrait of Nicholas Garry, the English-language namesake of the Garry oak tree, from the Archives of Manitoba, Canada.
A Garry oak in winter showing its unique branching.
Old growth Garry oak bark.
Garry oak leaf.
What are Garry oak’s growth characteristics?
A Garry oak can grow to be 60 feet high or more, with a trunk diameter up to 40 inches.
Most Garry oaks have a single trunk but can occasionally produce two or more trunks. The crown often appears to have a mushroom shape. Bark on a mature Garry oak is a silver-grey color, rough textured, with thick furrows.
Over time, tree branches will naturally take sharp twists or even corkscrew-like turns as the tree grows. This growing characteristic gives the Garry oak a distinct, contorted look that becomes more noticeable with age.
Garry oak leaves are leathery and deeply lobed with shiny, dark green tops and yellowish-green undersides. The tree is deciduous, with the leaves turning brown and falling in the autumn.
Once established, Garry oaks are naturally drought tolerant. They prefer sunny locations that will not be shaded by other trees.
Garry oak acorns and Garry oak leaves.
Garry oak catkins in spring.
Does a Garry oak use acorns to reproduce?
Separate male and female flowers are grown on the same tree. Long male flowers, called catkins, hang in strands from branches and are covered in yellow pollen grains. Tiny pink female flowers hold the tree’s eggs. Flowers are wind-pollenated in spring.
Beginning around age 30 years, a Garry oak will produce acorns. Acorns are the fruit of the oak tree. Acorns are usually 2.5-3 cm long, cup (cap) covering 1/5-1/4 of the nut. An olive-green color, acorns first appear mid-summer and continue to increase in size. They are oval to round in shape with a smooth surface. Once fully developed, acorns turn a coffee-brown color and begin to separate from the cap and fall from the tree. Acorns are edible, but must first be treated to leach out the bitter tannins from the nut.
Garry oaks produce many acorns per year.
Garry oak seedling sprouted from an acorn.
An intact Garry oak ecosystem in Oak Harbor on the Seaplane Navy Base. This is the only intact, native Garry oak ecosystem on Whidbey Island.
Native wildflowers shooting star and white fawn lily grow beneath old growth Garry oak trees in a Garry oak habitat.
Is Garry oak habitat valuable?
When it comes to habitat value, Garry oaks are a species of merit. The acorns they produce provide food for wildlife such as Western gray squirrels, turkeys, voles, various birds, and deer.
Due to their ecosystem plants, plus the lichens and mosses draping an oak’s trunk and branches, they provide a rich environment for insect communities. A healthy Garry oak can grow to be hundreds of years old.
Since time immemorial Coast Salish tribes have lived on the islands of the Salish Sea. The tribes cared for the natural environment, and Garry oaks thrived in the landscape providing acorns for food from the canopies above while wildflowers such as camas and chocolate lily grew below – all providing important carbohydrates to their diets.
These habitats were managed with frequent low intensity fires, and manually digging. Once the tribes were forced off their land these practices were substantially diminished while widespread logging and farming by settlers began to create huge impacts. Thus began the long decline of these important habitats.
Bibliography & Further Reading
Sept,, J. Duane (2011) Trees of the Northwest: Alaska, Western Canada and the Northwestern United States. China. Calypso Publishing Co. p.81
MacDonald, Carolyn (unknown) Garry Oak Ecosystems of British Columbia: an educator’s guide. BC, Canada. Wild BC, supported by Habitat Conservation Trust, p.19
de la Bedoyere, Camilla (2010) Acorn to Oak Tree. Irvine, CA. QEB Publishing, Inc. p. 14-16
Spellenberg, Earle and Nelson (2014) Trees of Western North America. Princeton, NJ. Princeton University Press. pp. 314-315
Deur, Douglas (2014) Pacific Northwest Foraging. China. Timber Press, Inc. p. 145
Bevis, Ken – Wildlife Biologist. Washington State Department of Natural Resources. Forest Stewardship Notes. Oregon White Oak: One Valuable Habitat Tree!. Considered, Feb. 7, 2020
Pavlik, B. M. (1991). Oaks of California. United States: Cachuma Press. p. 19-21
Alaback, P. B. (2004). Plants of the Pacific Northwest Coast: Washington, Oregon, British Columbia & Alaska. United States: Lone Pine Pub.. p. 50
British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development. (2020). Garry oak.
Multiple Authors (2018) Oregon White Oak and Wildlife Tools for Family Forestland Owners. Woodland Fish and Wildlife Group
Stein, William I. Tree Profile Garry Oak, Quercus garryana United States Forest Service
Peter J. Gould, Constance A. Harrington, Warren D. Devine “Growth of Oregon White Oak (Quercus garryana),” Northwest Science, 85(2), 159-171, (1 July 2011)
Devine, W.; Bower, A.; Miller, J.; Aubry, C. 2013. Oregon white oak restoration strategy for National Forest System lands east of the Cascade Range. Olympia, WA: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 98 p.
Julia Michalak “Effects of Habitat and Landscape Structure on Oregon White Oak (Quercus garryana) Regeneration Across an Urban Gradient,” Northwest Science, 85(2), 182-193, (1 July 2011)
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