A genus (Quercus) of trees, some of which are shrubby, with about 200 species, mainly in the Northern Hemisphere. About 50 species are native in the United States. All oaks have scaly winter buds, usually clustered at the ends of the twigs, and single at the nodes. The fruit is a nut (acorn). The leaves are simple and usually lobed.

Oaks furnish the most important hardwood lumber in the United States. Principal uses are for charcoal, barrels, building construction, flooring, railroad ties, mine timbers, boxes, crates, vehicle parts, ships, agricultural implements, caskets, woodenware, fence posts, piling, and veneer. Oak is also used for pulp and paper products.