Quercus is the tree genus that produces acorns, the familiar nuts of oak trees.
Quercus contains the oaks, a large genus of trees and shrubs in the beech family, Fagaceae. An acorn consists of a nut partly enclosed by a cup-like structure called a cupule. Oaks vary greatly in size, leaf shape, habitat, and growth rate.
Acorns are an important food for animals including squirrels, jays, deer, wild boar, and some insects. People have also eaten acorns after processing them to reduce tannins, bitter compounds that can irritate the digestive system.
Chestnuts and beeches are close relatives in Fagaceae, but they do not produce acorns. The word “oak” describes many Quercus species, including both deciduous and evergreen types distributed across the Northern Hemisphere and parts of the Southern Hemisphere.