283 Acorn Quercus The acorn, or oak nut, is the nut of the oaks and their close relatives. It usually contains a single seed (rarely 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 about 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. 19276 Acorn 283.jpg image/jpeg 65939 2012-04-20T09:33:52Z 310 Nuts Nuts Type 1 2011-02-09T00:37:30Z 2019-05-14T18:04:21Z false specific 3511 true FOOD00282