Pacif. Railr. Rep. 6: 28, 89, fig. 6. 1859.
Trees, deciduous, to 25 m. Bark dark-brown to black, ridges broad, irregular. Twigs brown to redbrown, (1.5-) 2-3.5 mm diam., glabrate. Terminal buds chestnut-brown, ovoid, 4-10 mm, glabrous or with scales ciliate on margins. Leaves: petiole 10-60 mm, glabrous to densely pubescent. Leaf-blade ovate or broadly elliptic to obovate, 60-200 × 40-140 mm, base cordate to obtuse, occasionally rounded, margins with 7-11 lobes and 13-45 awns, lobes acute to distally expanded, separated by deep sinuses, apex acute; surfaces abaxially glabrous with small axillary tufts of tomentum to densely pubescent, adaxially glabrous to minutely pubescent, veins raised on both surfaces. Acorns biennial; cup saucer-shaped to deeply bowl-shaped, 13-27 mm high × 20-28 mm wide, covering 1/2-2/3 nut, outer surface glabrous to sparsely puberulent, inner surface 1/3 to completely pubescent, scales more than 4 mm long, attenuate or acuminate to acute, smooth, occasionally tuberculate near base of cup, tips loose, especially at margin of cup; nut oblong to broadly ellipsoid, 21-34 × 14-22 mm, puberulent, especially at apex, scar diam. 5.5-10.5 mm. 2n = 24.
Phenology: Flowering late spring.
Habitat: On slopes and valleys of hills and mountains
Elevation: 300-2400 m
The abundant crops of acorns from Quercus kelloggii were at one time an important food source for Native Americans.
The species reportedly hybridizes with Quercus agrifolia (= Q. ×ganderi C. B. Wolf) and Q. wislizenii (= Q. ×morehus Kellogg).