Oregon Oak Quercus garryana

Oregon oak, also called Garry oak, is the only native oak in Washington and British Columbia (USFS Silvics of North America). It is a deciduous tree, usually 50 to 90 feet tall when mature (Silvics), with stout spreading branches, an open, rounded crown, deeply lobed leaves, and thick, furrowed bark.

Oregon oak is an ectomycorrhizal tree. Fungi recorded with it in the Pacific Northwest include the spring coccora (Amanita vernicoccora, in Washington under Garry oak and Douglas-fir), many Cortinarius and Russula species, and, rarely, the white king bolete (Boletus barrowsii), which is more usual under introduced oaks in towns (Siegel & Schwarz, Mushrooms of Cascadia). Chanterelle records are thin: Cantharellus cascadensis, normally a conifer species, has been found in woods almost entirely of Garry oak (M. Beug, via MycoMatch).

Oregon oak is drought-tolerant and well-adapted to the wet-winter, dry-summer climate of the Willamette Valley, Puget Sound lowlands, and the rain shadow of Vancouver Island. It grows on dry slopes, open prairies, and in savanna woodlands. In the Willamette Valley, fires, both natural and set by Indigenous people, maintained these open oak woodlands, savannas, and grasslands (Silvics).

The range stretches from Vancouver Island south through western Washington and Oregon to southern California (Silvics). In Washington, look for it in the San Juan Islands, south Puget Sound prairies, and the Columbia River Gorge. In Oregon, the Willamette Valley, Umpqua Valley, and Rogue Valley all support significant oak populations. In fall, oak woodlands are worth a look, but identify what you find carefully: toxic species also grow with Garry oak, including Tricholoma subannulatum and the red-pored bolete Rubroboletus eastwoodiae.

Associated Mushrooms

Many of the mushrooms recorded with Oregon oak are Cortinarius and Russula species. The spring coccora is the notable edible.

Spring Coccora

Amanita vernicoccora

Large and pale yellow, with a thick sac-like volva. Fruits in late winter and spring with oaks; in Washington, under Garry oak with Douglas fir (Tulloss). Because it is an Amanita — the genus that also contains the deadly destroying angels — only eat it if you can identify it with complete confidence.

Mycorrhizal Edible with Caution

Photos: Oregon Oak — Patrick Sowers (CC0).

Sources: Mushrooms of Cascadia (Siegel & Schwarz, 2024); MycoMatch (© Ian Gibson), a compilation of published descriptions through which most other field-guide authors named here are quoted.