The cultivation of plants, primarily trees, that produce nuts. The term nut is used loosely. Generally, a nut is defined as any edible fruit or seed enclosed in a hard shell. Botanically, a nut is a hard, indehiscent, one-seeded (nut), pericarp (shell) generally resulting from a compound ovary of a flower. Indehiscent means the shell does not split open spontaneously when ripe. Examples are chestnuts, filberts, and acorns. Technically, a nut is a dry edible fruit consisting of a kernel or seed enclosed in a woody shell. Only a fraction of the 80 fruits and seeds designated as nuts fit this description. The peanut is notable because the plant is a herbaceous annual legume in which the nuts are analogous to peapods that mature underground.