QUERCUS, in botany, a genus of the monocot polyandria class. The calix of the male has five segments; it has no corolla; and the stamens are from five to ten. The calix of the female is one entire, rough-leaf; it has no corolla; the style is from two to five; and the seed is ovate. There are 14 species, only one of them, viz. the robur, or common oak, a native of Britain.