The fagaceae (oak) family are a large group of trees and shrubs, also including beech, chestnut and chinquapin. Five genera are represented in the US, of which three occur in the West; chrysolepis (two species), notholithocarpus (one species) and quercus, with nearly 100 species. Plants are characterized by simple, stalked, alternate, pinnately-veined leaves, and tiny, monoecious flowers in dense spikes or clusters (often catkins). Fruits are nuts, one, two or three, completely or partially enclosed by cup-like or burr-like shells.