Quercus lobata aka Valley Oak

Quercus lobata, or valley oak, belongs to the oak family. This deciduous tree grows only in California in the wild. Its native range includes the Channel Islands. It grows in valleys, foothills, and woods along streams. Deep, rich soils support it across the Central Valley. Some trees live for 600 years.

Garden trees reach 50–70 feet [15–21 metres] in height. Their crowns spread 30–50 feet [9–15 metres] wide. Oregon State gives a broader height range of 30–90 feet [9–27 metres]. Large trees can exceed 100 feet [30 metres]. A short, thick trunk supports broad, arching limbs. Older branch tips may reach the ground. Gray bark develops deep cracks and block-shaped plates. Young twigs have fine hairs, which fade with age.

The green leaves grow one at a time along twigs. Each leaf has six to ten deep, rounded lobes. Fine hairs cover the pale lower surface. Crushed leaves give off a scent. Fall leaves turn yellow, orange, or copper brown. Small flowers appear from March through April. Each tree bears both male and female flowers. Male flowers hang in yellow-green catkins. Female flowers form small groups beside the leaves. Slender, pointed acorns sit in cups with thick, raised scales. They ripen from August to October within their first year.

Give this oak full sun and deep, fertile loam. It grows best where roots can reach groundwater. It suits hot, dry summers and cool, wet winters. Dry weather tolerance does not mean it needs little water. Oregon State notes that it needs a large water supply. Moist soil with good drainage suits it well. It accepts acid to neutral soil and some dry spells. North Carolina State lists USDA zones 7–9. Growth is moderate, but British trees may grow very slowly. Cool British summers can leave new wood prone to frost damage.

Its broad crown makes it useful as a shade tree. It also serves as a specimen or street tree. Surface roots can cause problems, and fallen material creates litter. Native wasps may form round galls on the twigs. Birds and mammals eat the acorns. Native American peoples used them as a staple food. Remove their tannins by leaching or boiling before eating them. North Carolina State rates the fruit's poison risk as low. Untreated acorns can cause gut pain and other illness. They can also block the digestive tract. Plants For A Future records traditional uses for bark and galls. These include remedies, tannin, and dye. The wood serves as fuel.