Valley Oak

The valley oak is a large, handsome oak with a thick, sturdy trunk and broad crown of weeping branches. The tree can grow up to 100 feet in height, supported by a stout trunk, which may exceed 3 meters in diameter. The branches, which droop with age, have an irregular, spreading, arch-like shape that creates a gorgeous silhouette. The thick, whitish gray bark is distinctly ridged like alligator skin. The matte green leaves have deep, round lobes and a pale underside coated in velvety, white fuzz. The leaves are 5-10 cm wide and about two times as long as they are wide. The inconspicuous flowers are produced on drooping green catkins. The large acorns, 2-3 cm long, have deep stippled caps. Most commonly produced in singlets, the acorns turn from light green to dark brown once they fall.

Basic Information

• Member of the Fagaceae, or beech, family

• Winter deciduous

• Can live over 600 years

• Largest of the North American oaks

• Grow quickly, reaching 20 feet in 5 years, 40 feet in 10 years, and up to 60 feet in 20 years

Habitat

• Native from Siskiyou County south to San Diego County

  • Endemic to California (ie. grows only in California)

  • Commonly found in the Central Valley and other smaller valleys throughout California, as well as on Santa Cruz and Catalina Iisland

• Commonly found in open valley savannas, chaparral, and mixed woodland

  • Primarily grows in hot valleys where there is a water table within reach of the roots

Ecological Role

• A wide variety of wildlife consume to acorns, including the acorn woodpecker, California scrub jay, yellow-billed magpie, and California ground squirrel

• Oak galls, which are frequently attached to twigs and leaves, house the larva of the small indigenous wasps Andricus quercuscalifornicus and A. kingi

• Host plant for a number of moths and butterflies including: California Sister, Propertius Duskywing, Mournful Duskywing, Golden Hairstreak, and Gold-Hunter's Hairstreak

  • Only known food plant of Chionodes petalumensis caterpillars

Reproduction

• Blooms from March-May

• Monoecious, with male and female flowers on the same tree

• Acorns fall in October

Alternative Names

• Roble

Historical Uses

• The acorns were consumed in the form of a meal or bread by many tribes including the Kawaiisu, Mendocino Indian, Miwok, Pomo, and Tubatulabal

• The Kawaiisu used a poultice of the galls and salt applied to burns, sores, and cuts

• The Concow as used the bark to create a dye for basket-making

• The Yuki used the bark to treat diarrhea

• The Miwok used the pulverized outer bark for sores and umbilicus, and a decoction for cough medicine

• The wood was also used as a building material

Additional Information

• The Douglas fir is the second tallest conifer in the world, behind only the Coast Redwood

  • The tallest recorded tree was 393 feet tall

  • Prior to massive logging, Douglas firs often grew over 300 ft tall, though some ~1000-year-old titans like surpassed 400 ft in height

  • Douglas-fir may have been the tallest tree species on the planet; however, so many trees were lost to logging that it is impossible to know now

• The tree trunk can reach a diameter 4.5-6 meters, or 15-20 feet

• best timber-producing species in North America, yielding more timber than any other species on the continent

• Many of the oldest stands of Douglas fir have been ravaged by logging, resulting in massive loss of habitat and ecosystem devastation

  • The few remaining patches of rapidly shrinking old growth are not large enough to support the animals and plants that previously relied on them