Typically, leaves are five to ten centimeters in length and are roundly but 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 ciliae, yielding a velvety feeling. When a fresh leaf is rubbed or broken, an aromatic scent is exuded, evoking a forest odor. The wood is a dullish brown approaching yellow, and it has not been used extensively for milling.Acorn and leaves
Over most of the range, acorns fall in October. A variety of mammals and birds harvest these morsels, including the Acorn Woodpecker, Yellow-billed Magpie, and California ground squirrel. They are so efficient in storing acorns for winter that it can be difficult to find remnant acorns under the tree by January. The acorns are medium to dark brown and range from two to three centimeters in length. The caps have deep stippling and are found most often as singlets, but occasionally as doublets.
Globular galls are frequently attached to limbs of mature specimens of Valley oak. These house the larval stage of small indigenous wasps. The valley oak is the only known foodplant of Chionodes petalumensis caterpillars.
 Distribution and habitat
Valley oak tolerates cool wet winters and hot dry summers, but requires abundant water for its thirsty root system. It is most abundant in rich deep soils of valley floors below 600 meters in elevation. Valley oak is found in dense riparian forests, open foothill woodlands and valley savannas. Commonly associated trees are Coast live oak, Interior live oak, Blue oak, Black walnut, California Sycamore and Digger pine.
The Valley oak is widely distributed in: the California Central Valley; many smaller valleys such as the San Fernando Valley (original Spanish place-name from oak savannah), Conejo Valley, and Santa Ynez Valley; the Inner Coast Ranges south of the Eel River; and the Transverse Ranges from the Tehachapi Mountains to the Simi Hills, Santa Susana Mountains. It is also present on Santa Cruz Island and Catalina Island in the Pacific Ocean. Some of the most picturesque stands are found in Sonoma Valley, Round Valley in Mendocino County and the southern Salinas Valley near the up-river reaches of the Salinas River.
Valley oak is of the White oak evolutionary lineage, which is officially known as the subgenus Lepidobalanus. This subgenus comprises numerous oaks from California and elsewhere, which species share similar leaves, acorns, bark and wood pulp. Early settlers used a variety of common names for the Valley oak including: White oak, bottom oak, swamp oak, water oak and mush oak. The Spaniards, thinking the tree looked like the white oaks in Europe, called the tree "roble".Leaves of Quercus lobata
 Historical accounts
In 1796, the English explorer George Vancouver noted on his expedition through the Santa Clara Valley, after seeing an expanse of Valley oaks: "For about twenty miles it could only be compared to a park which had originally been closely planted with the true old English oak; the underwood, that had probably attended its early growth, had the appearance of having been cleared away and left the stately lords of the forest in complete possession of the soil which was covered with luxuriant foliage."
In the year 1861, William Henry Brewer, the chief botanist for the first California Geological Survey wrote of the Valley oaks that he saw in Monterey County: "First I passed through a wild canyon, then over hills covered with oats, with here and there trees--oaks and pines. Some of these oaks were noble ones indeed. How I wish one stood in our yard at home....I measured one [Valley Oak] with wide spreading and cragged branches, that was 26.5 feet in circumference. Another had a diameter of over six feet, and the branches spread over 75 feet each way. I lay beneath its shade a little while before going on."
The Hooker Oak of Chico, California, was once the largest known Valley Oak. When it fell on May 1, 1977, it was nearly a hundred feet tall (30 m) and 29 feet (8.8 m) in circumference eight feet (2.4 m) from the ground.
The Tragedy Oak in Hanford, California, was at the same place where the historic Mussel Slough Tragedy gun fight happened in 1880. Six victims of the shooting were carried to the porch of the Brewer house, which was shaded by a tall oak tree. The tree became famously known as the Tragedy Oak. Sadly the tree fell down in a storm in 1995. A part of its trunk was donated by the Warmerdam family, that then owned the land that it grew on, to a nearby school called Pioneer Elementary School.