The family
Fagaceae includes
beeches and
oaks, and comprises about 600 species of both
evergreen and
deciduous trees and shrubs, which are characterized by alternate simple
leaves with pinnate venation, unisexual
flowers in the form of
catkins, and fruit in the form of cup-like (
cupule) nuts. Fagaceous leaves are often lobed and both
petioles and
stipules are generally present. Fruits lack
endosperm and lie in a scaly or spiny husk that may or may not enclose the entire nut, which may consist of one to seven seeds. The best-known group of this family is the
oaks, genus
Quercus, the fruit of which is a non-valved nut (usually containing one seed) called an acorn. The husk of the acorn in most oaks only forms a cup in which the nut sits. Fagaceae are one of the most ecologically important woody plant families in the Northern Hemisphere, as oaks form the backbone of temperate forests in North America, Europe, and Asia and one of the most significant sources of wildlife fodder.