Most of the following valley oak facts were gleaned from the publication
OAKS OF CALIFORNIA from Cachuma Press

Valley Oaks, Quercus lobata, native
- a dicot in the Fagaceae family -
canopy of Valley oak west of weir on #1 Loop Trail
Click here for more Valley Oak Tree images

  • Quercus lobata - Latin / botanical name for Valley Oak. Common name - mush oak
  • (Quercus-Latin for oak); quer (Celtic)- meaning fine, cuez (Celtic) - meaning tree, lobata (Latin)- meaning deeply lobed 
  • Valley Oak grows only in California , generally below 2,500 feet elevation.
  • Valley Oaks are the largest of all oak trees in North America. They can rise more than 100 feet above the ground and have trunks 6 or 7 feet in diameter.
  • A valley oak in Gridley, California had a trunk 9 feet in diameter and was more than 600 years old. It was felled in the 1990's.
  • Trees with 3 to 4 foot diameter trunks are only 150-250 years old.
  • Valley oak trees are deciduous - meaning they lose their leaves in fall.
  • Valley Oaks need large amounts of water at root depth + rich soil produced by spring flooding to survive in the Central Valley's severe summers.
  • ROOT SYSTEM: A young (10-40 years old) valley oak's tap root can reach 60 feet deep, to search for groundwater. But as the tree matures, the tap root sloughs off and the tree develops a tiered root system with feeder and sinker roots that permeate different layers in the soil profile, generally from two to four feet below the soil surface. Some of these roots extend out more than twice the drip line. This allows the tree to avoid, rather than endure drought. (TNC; Oaks: California's Lost Legacy, Graham Chisholm, 1987)
  • Individual trees produce both male and female flowers and are wind pollinated.
  • valley oaks bloom in late March and April at KOPCross pollination from different oak species does not produce viable acorns.

  • The valley oaks at KOP bloom in late March and into April.
  • The acorn of the Valley Oak is long (up to 2") and pointed and is the dry fruit of the tree. 
  • Mature Valley Oaks can produce up to a ton of acorns in a good year.
  • Valley Oaks are heavy producers in alternating years.
  • Squirrels, Scrub Jays and Acorn Woodpeckers eat most of the acorns, insects and fungus destroy many.
  • Acorns were the Yokuts (pronounced: ´Yo-kotch with emphasis on first syllable and both o's having a long "o" sound) Indian main food staple, mixed with other types of acorns to improve taste, ground, leeched of tannins and made into a mush, cake or flat bread.
  • Oak Apples (really wasp galls) were collected, stored and used by the Yokuts Indians for tinder.
  • Kaweah Oaks Preserve has many wasps, but 7 special wasps lay their eggs on (or in) the leaves or stems of the Valley oaks in the spring. The tree then forms interesting galls for the larva.

  • Click here to view images of the seven galls.


UC Cooperative Extension - Integrated Hardwood Range 
                                 Management Program

California Oak Foundation

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