The
acorn, or
oak nut, is the
nut of the
oaks and their close relatives (genera
Quercus and
Lithocarpus, in the family
Fagaceae). It usually contains a single
seed (occasionally two seeds), enclosed in a tough, leathery shell, and borne in a cup-shaped
cupule. Acorns vary from 1–6 cm long and 0.8–4 cm broad. Acorns take between 6 and 24 months (depending on the species) to mature; see
List of Quercus species for details of oak classification, in which acorn
morphology and
phenology are important factors.
