This article is about nuts in botany. For foods called nuts, which may not be true botanical nuts, seeNut (food). For other kinds of nut, seeNut (disambiguation).
Fruit with outer shell protecting kernel
Anut is afruit consisting of a hard or toughnutshell protecting a kernel which is usually edible. In general usage and in a culinary sense, many dryseeds are called nuts, but in a botanical context, "nut" implies that the shell does not open to release theseed (indehiscent).[1]
Most seeds come from fruits that naturally free themselves from the shell, but this is not the case in nuts such ashazelnuts,chestnuts, andacorns, which have hard shell walls and originate from a compound ovary.[2]
A seed is the mature fertilisedovule of a plant; it consists of three parts, theembryo which will develop into a new plant, stored food for the embryo, and a protective seed coat.Botanically, a nut is a fruit with a woodypericarp developing from asyncarpousgynoecium. Nuts may be contained in aninvolucre, a cup-shaped structure formed from the flowerbracts. The involucre may be scaly, spiny, leafy or tubular, depending on the species of nut.[3] Most nuts come from thepistils withinferior ovaries (seeflower) and all areindehiscent (not opening at maturity). True nuts are produced, for example, by some plant families of theorderFagales. These includebeech (Fagus),chestnut (Castanea),oak (Quercus),stone-oak (Lithocarpus) andtanoak (Notholithocarpus) in the familyFagaceae, as well ashazel,filbert (Corylus) andhornbeam (Carpinus) in the familyBetulaceae.
A small nut may be called a "nutlet" (formerly called a nucule,[4] a term otherwise referring to theoogonium ofstoneworts[5]). Inbotany, the term "nutlet" can be used to describe apyrena or pyrene, which is aseed covered by a stony layer, such as the kernel of adrupe.[6] Walnuts andhickories, includingpecans, (Juglandaceae) have fruits that are difficult to classify. They are considered to be nuts under some definitions but are also referred to asdrupaceous nuts.[3]
Nuts used for food are a common source of food allergens.[7] Reactions can range from mild symptoms to severe ones, a condition known asanaphylaxis, which can be life-threatening. The reaction is due to the release ofhistamine by the body in response to anallergen in the nuts, causingskin and other possible reactions.[8] Tree nut allergies are distinct frompeanut allergy, aspeanuts arelegumes, whereas a tree nut is a hard-shelled nut; however, experts suggest that a person with an allergy to peanuts should avoid eating tree nuts, and vice versa.[7][9]
Nuts contain the diverse nutrients that are needed for the growth of a new plant.[7] Composition varies, but they tend to have a low water andcarbohydrate content, with high levels of fats,protein,dietary minerals, andvitamins.[7]
AnEastern chipmunk (Tamias striatus) with a hazelnut in its mouth
Nuts are eaten by humans and wildlife.[7] Because nuts generally have a high oil content, they are a significant energy source.[7] Many seeds are edible by humans and used in cooking, eaten raw, sprouted, or roasted as asnack food, soaked in water and filtered to makenut milk, ground to make nut butters, or pressed for oil that is used in cooking and cosmetics.[7]
^Alasalvar, Cesarettin; Shahidi, Fereidoon (17 December 2008).Tree Nuts: Composition, Phytochemicals, and Health Effects (Nutraceutical Science and Technology). CRC. p. 143.ISBN978-0-8493-3735-2.
^abArmstrong, W.P. (15 March 2009)."Fruits Called Nuts". Palomar College.Archived from the original on 7 November 2021. Retrieved28 June 2021.
^abcdefgh"Nuts". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, OR. 1 September 2018.Archived from the original on 28 March 2019. Retrieved28 March 2019.
^Harding, Mary."Nut Allergy". Patient.Archived from the original on 30 January 2022. Retrieved10 July 2021.
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