From the U.S. Forest Service:

"Oregon white oak is a deciduous tree or sometimes a shrub. Growth form can be affected by regional and site conditions. Oregon white oak may be 30 to 100 feet (8-30 m) tall with a solitary trunk or up to 20 feet (5 m) tall with many trunks. In tree form, Oregon white oak's DBH is typically 24 to 40 inches (61-100 cm), although a DBH of 97 inches (250 cm) was reported in a review. Oregon white oak trunks have thick, furrowed, scaly bark. A short, crooked, and sometimes creeping form is described in rocky habitats with shallow soils. At high-elevation sites in eastern Oregon and Washington, a "shrubby" growth form is typical. A shrub form is also noted from the southernmost populations. Thilenius described "forest-form" and "savannah-form" trees in Willamette Valley. Forest-form trees were fairly tall with ascending branches near the crown and a DBH often less than 24 inches (60 cm). These trees grew in closed-canopy woodlands with nearly 1,045 trees/ha. Savannah-form trees had DBH measurements often exceeding 3 feet (1 m), massive branches, and spreading crowns. These trees grew in open woodlands with 17 trees/ha.

Leaves are moderately to deeply lobed and measure up to 6 inches (15 cm) long. Generally there are 3 to 7 pinnate lobes. Margins are entire or with 2 to 3 teeth. Occasionally, trees produce a second set of summer leaves. Male flowers are catkins that are produced on the current year's growth. Female flowers are solitary or in clusters and appear in the leaf axils of new twigs. Oregon white oak produces large acorns that measure 0.8 to 1.2 inches (2-3 cm) long and mature in a single growing season. Five hundred years is the estimated Oregon white oak lifespan. Growth rates evaluated in an 80-year-old Oregon white oak-Douglas-fir stand in Oregon State's McDonald-Dunn Forest decreased by over half after the first 20 years of life. Overtopping by Douglas-fir may have affected growth."