page_title: Quercus lobata
section_title: Description and ecology
hierarchical_section_title: Quercus lobata / Description and ecology
caption_attribution_description: English: Valley oak acorn and leaves
context_page_description: Quercus lobata, commonly called the valley oak or roble, grows into the largest of North American oaks. It is endemic to California, growing in interior valleys and foothills from Siskiyou County to San Diego County. Mature specimens may attain an age of up to 600 years. This deciduous oak requires year-round access to groundwater.
  Its thick, ridged bark is characteristic and resembles alligator hide. The valley oak's deeply lobed leaves assist in identification.
context_section_description: The sturdy trunk of the valley oak may exceed three meters (10 feet) in diameter and its stature may surpass 30 meters (100 feet) in height. The "Henley Oak", in Covelo, California, is the tallest known North American oak, at 153 feet (47 m).
  The branches have an irregular, spreading and arching appearance that produce a profound leafless silhouette in the clear winter sky. During Autumn leaves turn a yellow to light orange color but become brown during mid to late fall. In advancing age the branches assume a drooping characteristic. Its pewter-colored rippled bark adds to the attractive aesthetic of this species.
  Typically, leaves are five to ten centimeters (2–4 inches) long and are roundly and deeply lobed. The leaf width is approximately one half its length. Each leaf is matte green with an underneath pale green appearance; moreover, the leaf is covered with abundant soft fuzz, yielding an almost velvety feeling. When a fresh leaf is rubbed or broken, an aromatic scent is exuded, evoking a forest odor. The wood is a dull brown approaching yellow, and it has not been used extensively for milling.
  Over most of the range, acorns fall in October. A variety of mammals and birds eat them, including the acorn woodpecker, California scrub jay, yellow-billed magpie, and California ground squirrel. The acorns are also attacked by bruchid beetles, but can survive moderate levels of infestation. Surviving acorns all germinate in their first winter, and none remain by mid-winter. The acorns are medium to dark brown and range from two to three centimeters (0.8–1.2 inches) in length. The caps have deep stippling and are found most often as singlets, but occasionally as doublets. The Concow tribe call the acorns lō-ē’ (Konkow language).
  Globular galls up to several centimeters in diameter are frequently attached to twigs of mature specimens of valley oak. These house the larval stage of small indigenous wasps Andricus quercuscalifornicus.  A related wasp species, A. kingi, produces small galls shaped like Hershey's kisses on leaf surfaces. The valley oak is the only known food plant of Chionodes petalumensis caterpillars.
  Like many oaks, valley oaks can tolerate wild fires. Although smaller individuals may be top-killed, most resprout from the root crown.
caption: Acorn and leaves
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