Acorn

This article is about the nut. For the squash, see Acorn squash. For other uses, see Acorn (disambiguation).

English oak acorn
Acorns of the willow oak in South Carolina (from small to large, counterclockwise from center): Q. phellos (willow oak), Q. falcata (southern red oak; top right), Q. alba (white oak), and Q. coccinea (scarlet oak). Scale bar at upper right is 1 cm.
Diagram of the anatomy of an acorn: A.) Cupule B.) Pericarp (fruit wall) C.) Seed coat (testa) D.) Cotyledons (2) E.) Plumule F.) Radicle G.) Remains of style. Together D., E., and F. make up the embryo.

The acorn is the nut of the oaks and their close relatives (genera Quercus and Lithocarpus, in the family Fagaceae). It usually contains a seedling surrounded by two cotyledons (seedling leaves), enclosed in a tough shell known as the pericarp, and borne in a cup-shaped cupule.[1][2] Acorns are 1–6 cm (1⁄2–2+1⁄2 in) long and 0.8–4 cm (3⁄8–1+5⁄8 in) on the fat side. Acorns take between 5 and 24 months (depending on the species) to mature; see the list of Quercus species for details of oak classification, in which acorn morphology and phenology are important factors.

  1. ^ Dietland Müller-Schwarze (2009). Hands-On Chemical Ecology:: Simple Field and Laboratory Exercises. Springer Science & Business Media. p. 32. ISBN 978-1-4419-0378-5.
  2. ^ "Acorn | Definition & Facts". Encyclopedia Britannica. Retrieved 28 April 2024.