{{About|nuts in botany|foods called nuts, which may not be true botanical nuts|Nut (food)|other kinds of nut|Nut (disambiguation)}}{{Short description|Fruit with outer shell protecting kernel}} {{pp-move-indef}} {{Use dmy dates|date=August 2021}} A '''nut''' is a fruit consisting of a hard or tough nutshell protecting a kernel which is usually edible. In general usage and in a culinary sense, many dry seeds are called nuts, but in a botanical context, "nut" implies that the shell does not open to release the seed (indehiscent).<ref>{{cite web |url=https://www.britannica.com/science/nut-plant-reproductive-body |title=Nut: Plant reproductive body |publisher=Encyclopedia Britannica |date=6 June 2024 |access-date=1 July 2024}}</ref>
Most seeds come from fruits that naturally free themselves from the shell, but this is not the case in nuts such as hazelnuts, chestnuts, and acorns, which have hard shell walls and originate from a compound ovary.<ref name="tree_nuts_composition_phytochemicals_and_health_effects">{{Cite book |last1=Alasalvar |first1=Cesarettin |last2=Shahidi |first2=Fereidoon |title=Tree Nuts: Composition, Phytochemicals, and Health Effects (Nutraceutical Science and Technology) |date=17 December 2008 |publisher=CRC |isbn=978-0-8493-3735-2 |page=143}}</ref>
== Definition == [[File:Caov2 002 phd.jpg|thumb|alt=black and white cross-section drawing of a shagbark hickory nut|Diagram of a shagbark hickory nut ]] A seed is the mature fertilised ovule of a plant; it consists of three parts, the embryo 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 woody pericarp developing from a syncarpous gynoecium. Nuts may be contained in an involucre, a cup-shaped structure formed from the flower bracts. The involucre may be scaly, spiny, leafy or tubular, depending on the species of nut.<ref name=Palomar>{{cite web |url=https://www2.palomar.edu/users/warmstrong/ecoph8.htm |title=Fruits Called Nuts |author=Armstrong, W.P. |date=15 March 2009 |publisher=Palomar College |access-date=28 June 2021 |archive-date=7 November 2021 |archive-url=https://web.archive.org/web/20211107151123/https://www2.palomar.edu/users/warmstrong/ecoph8.htm |url-status=live}}</ref> Most nuts come from the pistils with ''inferior'' ovaries (see flower) and all are ''indehiscent'' (not opening at maturity). True nuts are produced, for example, by some plant families of the order Fagales. These include beech (''Fagus''), chestnut (''Castanea''), oak (''Quercus''), stone-oak (''Lithocarpus'') and tanoak (''Notholithocarpus'') in the family Fagaceae, as well as hazel, filbert (''Corylus'') and hornbeam (''Carpinus'') in the family Betulaceae. [[File:Très serré.jpg|thumb|180px|An Eastern chipmunk (''Tamias striatus'') with a hazelnut in its mouth]]
A small nut may be called a "nutlet" (formerly called a nucule,<ref name=nucule>E.g., {{Citation |last=Lindley |first=John |author-link=John Lindley |title=The Vegetable Kingdom |publisher=Bradbury and Evans |date=1846 |location=London |pages=66 |url=https://books.google.com/books?id=ybw9AAAAYAAJ}}; compare {{cite web |url=https://www.wildflowers-and-weeds.com/Plant_Families/Verbenaceae.htm |title=Verbenaceae: Plants of the Verbena Family |last=Elpel |first=Thomas J. |date=1997–2021 |website=Wildflowers-and-Weeds.com |access-date=28 April 2024}} The term ''nucula'' was applied specifically to hazelnuts (''Corylus'') in {{cite book |last=Watson |first=P. W. |author-link=Peter William Watson |title=Dendrologia Britannica |publisher=Author |date=1825 |location=London |pages=xlix |url=https://books.google.com/books?id=J2Q-AAAAcAAJ}}</ref> a term otherwise referring to the oogonium of stoneworts<ref name=stonewort>{{cite book |last=Lindley |first=John |author-link=John Lindley |title=An Introduction to the Natural System of Botany |publisher=G & C & H Carvill |date=1831 |location=New York |pages=323 |url=https://books.google.com/books?id=Q2QaAAAAYAAJ}}</ref>). In botany, the term "nutlet" can be used to describe a pyrena or pyrene, which is a seed covered by a stony layer, such as the kernel of a drupe.<ref name=pyrena>{{cite web |url=https://www.mobot.org/mobot/latindict/keyDetail.aspx?keyWord=drupe |title=A Grammatical Dictionary of Botanical Latin s.v. Drupe |last=Eckel |first=P. M. |date=2010–2023 |publisher=Missouri Botanical Garden |access-date=28 April 2024}}</ref> Walnuts and hickories, including pecans, (Juglandaceae) have fruits that are difficult to classify. They are considered to be nuts under some definitions but are also referred to as drupaceous nuts.<ref name="Palomar" />
== Toxicity == {{See also|Tree nut allergy}} Nuts used for food are a common source of food allergens.<ref name="lpi">{{cite web |title=Nuts |publisher=Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, Oregon|url=https://lpi.oregonstate.edu/mic/food-beverages/nuts |date=2025|access-date=20 December 2025}}</ref> Reactions can range from mild symptoms to severe ones, a condition known as anaphylaxis, which can be life-threatening. The reaction is due to the release of histamine by the body in response to an allergen in the nuts, causing skin and other possible reactions.<ref>{{cite web |author=Harding, Mary |title=Nut Allergy |url=https://patient.info/allergies-blood-immune/food-allergy-and-intolerance/nut-allergy |url-status=live |archive-url=https://web.archive.org/web/20220130123419/https://patient.info/allergies-blood-immune/food-allergy-and-intolerance/nut-allergy |archive-date=30 January 2022 |access-date=10 July 2021 |publisher=Patient}}</ref> Tree nut allergies are distinct from peanut allergy, as peanuts are legumes, 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.<ref name="lpi" /><ref>{{cite web |title=Common Food Allergens |url=http://www.foodallergy.org/allergens/index.html |url-status=dead |archive-url=https://web.archive.org/web/20070613040928/http://www.foodallergy.org/allergens/index.html |archive-date=13 June 2007 |access-date=24 June 2007 |publisher=Food Allergy Research & Education}}</ref>
== Consumption as food == {{Main|Nut (food)}} thumb|180px|Walnut kernels
For wildlife and humans, nuts supply a relatively large quantity of calories from unsaturated fats, such as linoleic acid and linolenic acid, and monounsaturated fats.<ref name=lpi/> Nuts are rich sources of B vitamins, vitamin E, and essential amino acids.<ref name=lpi/>
Although nutrient composition varies slightly among different nuts, they generally have low water and carbohydrate content, with high levels of protein, dietary minerals, and dietary fiber.<ref name="lpi" />
Many nuts and seeds are edible and used in cooking, eaten raw, sprouted, or roasted as a snack food, soaked in water and filtered to make nut milk, ground to make nut butters, or pressed for oil that is used in cooking and cosmetics.<ref name="lpi" />
==See also== {{columnslist|colwidth=30| * Nut (food) * List of culinary nuts * List of edible seeds * Nutmeg * Nutcracker * Achene }}
==References== {{reflist}}
== Further reading == * Albala, Ken (2014) ''Nuts A Global History''. The Edible Series. {{ISBN|978-1-78023-282-9}}
{{Nuts}} {{Fruits}} {{Non-timber forest products}} {{Authority control}}
Category:Fruit morphology Category:Edible nuts and seeds