An evergreen oak, varying in the wild from a mere shrub to a tree 70 or more ft high; young shoots furnished with a loose, scattered, starry down. Leaves oblong to ovate, rounded or slightly heart-shaped at the base, terminated and edged with slender, spiny teeth, 1 to 23⁄4 in. long, 1⁄2 to 13⁄4 in. wide, often entire on adult native trees, both sides shining green and quite glabrous; stalk 1⁄8 to 1⁄4 in. long, downy, the stellate down often continued down the midrib. Acorn 3⁄4 to over 1 in. long, about 1⁄3 in. wide, two-thirds enclosed in a cup with thin, downy, flattened scales, ripening the second year.
Native of California; introduced to Kew in 1874, where it has proved hardy but slow-growing. It has also borne acorns there. In its glossy green leaves, glabrous on both surfaces, it resembles only Q. coccifera, but the tree is of much more open habit, and the leaves are larger. Henry has also pointed out differences in the shape of the buds; in Q. wislizenii they are conical, pointed, and longer than the rounded blunt ones of Q. coccifera. In the allied Q. agrifolia the leaves are convex above, with conspicuous tufts of hairs in the vein-axils beneath, and the fruits ripen in one season.
The example at Kew, pl. 1874, measures 40 × 21⁄2 ft (1973). It has spiny leaves, but on a tree in the Sunningdale Nurseries, about 35 ft high, they are almost entire.