Oregon White Oak
 

Mature Size, Growth, Longevity

50-90' tall, 50-70' wide, w/ a short, massive, branching trunk & a broad, wide-spreading, rounded crown. Has grown to 120' tall. Slow growing, less than 12"/year. Very long-lived, to 500 yrs.

Native Range

U.S. Native — Native from Vancouver Island and the Fraser River Valley in Canada, south to W. Washington, W. Oregon, & California coast north of San Francisco, at elevations to 6,000 feet.

Flower and Fruit Details

Monoecious flowers; male flowers greenish-yellow catkins. Blooms later than nearby associate species, often in April-May at the base of new shoots as new foliage emerges, and expanding to 1-4" in length. Small red female flowers in new leaf axils. The fruit is a 1-1.2" long acorn (nut), half as wide, maturing in one growing season, sessile or w/ a very short stalk, thick and rounded at the top, with a sweet kernel and a hairy cap ("cup"). Acorns ripen Sept-Nov. Food for woodpeckers & wild turkeys.

Leaf and Bark Features

Deciduous: Leaves are simple, deciduous, obovate to oblong, 3-6" long, with 5-9 lobes, and deeply cut sinuses. Lobes and sinuses are rounded (white oak group). Leaves are leathery, dark green above, hairy and paler green beneath. Golden-yellow fall color. Bark is very thick, up to one inch on an old tree (fire-resistance) with broad ridges divided by shallow fissures, separating into light brown or gray scales. Smaller twigs are stout, orange-red and hairy, then turning reddish-brown and smooth with age.

Culture and Care

Needs full sun. Will not tolerate shade. Very heat & drought-tolerant. Does well on exposed, droughty sites. Tolerates very wet winter soils. Does well in clay soils. Zones (6)7-9. Few pests/diseases. Tent caterpillars, borers, gall wasps, oak anthracnose, root & trunk rots are possible problems.

Strengths, Weaknesses, Other Facts

Strong branches. Very resistant to damage from ice and snow loads. Good wildlife value. 3-season interest: Spring, summer, & fall. Leaf protein content for wildlife & livestock is similar to that of alfalfa. Found in native stands near alders, bigleaf maple, douglasfir and ponderosa pine.

Suggested Uses

Use as a shade tree.

Taxa and Plants of this Species at BCA