Valley Oak
 

Mature Size, Growth, Longevity

One of the largest of western oaks, reaching up to 100' tall & 60' wide, with a stout trunk up to 10' in diameter. Develops huge branches with arching, spreading limbs. Becomes weeping w/ age. The champion tree in California is 120' tall and 100' wide. A fast grower, up to 4' per year. Long-lived, to 400-600 years.

Native Range

U.S. Native — Native and endemic to central and western California.

Flower and Fruit Details

Monoecious spring flowers; males in catkins, cream to green in color. Fruit is a 1-1.5" acorn, maturing in one season, nut is slender & pointed, on a short stalk, single or in pairs, enclosed 1/3 in a hairy cap (cup), w/ a sweet kernel. Woodpeckers, jays & deer eat the fruits.

Leaf and Bark Features

Deciduous: Leaves pubescent & dark green above, pale/pubescent below, w/ 7-11 prominent, oblique, rounded lobes w/ deeply cut, rounded sinuses (nearly to the midrib), thus the name, "lobata". Leaves simple, deciduous, leathery-textured, 2.5-4" long, oblong/ovate. Fall color is yellow or light-orange, and then brown. As the tree ages, the bark becomes quite thick, scaly and light gray in color, and divided into broad, flat plates with cross-cut grooves, giving them a squarish appearance like alligator hide. Young twigs slender, hairy, red-brown to gray.

Culture and Care

Grows best in moist, deep, rich soils, but will grow well in other soils if moisture is sufficient. Heat-tolerant. Not drought-tolerant. Needs full sun. Tolerates soil pH 6.0-8.0. Use organic mulch. Zones 5-9. Few pest & disease problems. Galls.

Strengths, Weaknesses, Other Facts

Host plant for butterflies. Good wildlife value. 4-season interest: Spring, summer, fall, winter. Weak-wooded. Tends to drop branches. Somewhat messy. Leaves release an aromatic fragrance when rubbed. Old trees create an interesting winter silhouette. Often grows near black walnut, willows & blackberries.

Suggested Uses

Specimen, shade tree. Used in bird/butterfly gardens.

Taxa and Plants of this Species at BCA