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A nut is a
fruit In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the ...

fruit
consisting of a hard or tough
nutshell Korean pine nuts — shelled, and shell, above; unshelled, below A nutshell is the outer shell of a nut Nut often refers to: * Nut (fruit), a fruit composed of a hard shell and a seed * Nut (food), collective noun for dry and edible fruits or see ...

nutshell
protecting a kernel which is usually edible. In general usage and in a culinary sense, a wide variety of dry seeds are called nuts, but in a botanical context "nut" implies that the shell does not open to release the seed (
indehiscent 200px, Dehiscence of the follicular fruit of milkweed ('' Asclepias syriaca'') revealing seeds within Dehiscence is the splitting of a mature plant structure along a built-in line of weakness in order to release its contents. This is common among ...
). Most seeds come from fruits that naturally free themselves from the shell, but this is not the case in nuts such as
hazelnut The hazelnut is the nut (fruit), fruit of the hazel, hazel tree and therefore includes any of the nuts deriving from species of the genus ''Corylus'', especially the nuts of the species ''Corylus avellana''. They are also known as cobnuts or ...

hazelnut
s,
chestnut The chestnuts are the deciduous In the fields of horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticulturists are agriculturis ...

chestnut
s, and
acorn The acorn, or oaknut, is the nut Nut often refers to: * Nut (fruit), a fruit composed of a hard shell and a seed * Nut (food), collective noun for dry and edible fruits or seeds * Nut (hardware), a fastener used with a bolt Nut or Nuts may al ...

acorn
s, which have hard shell walls and originate from a compound ovary. The general and original usage of the term is less restrictive, and many nuts (in the culinary sense), such as
almond The almond (''Prunus dulcis'', syn. ''Prunus amygdalus'') is a species of tree native to Iran Iran ( fa, ایران ), also called Persia, and officially the Islamic Republic of Iran, is a country in Western Asia Western Asia, ...

almond
s,
pecan The pecan (''Carya illinoinensis'') is a species of hickory native to the southern United States and northern Mexico in the region of the Mississippi River. The tree is cultivated for its seed in the southern United States, primarily in Georgia ...

pecan
s,
pistachio The pistachio (, ''Pistacia vera''), a member of the cashew family, is a small tree originating from Central Asia Central Asia is a region in Asia which stretches from the Caspian Sea in the west to China and Mongolia in the east, and from Afg ...

pistachio
s,
walnut A walnut is the Nut (fruit), nut of any tree of the genus ''Juglans'' (family Juglandaceae), particularly the Persian or English walnut, ''Juglans regia''. A walnut is the edible seed of a drupe, and thus not a true botanical nut. It is com ...

walnut
s, and
Brazil nut The Brazil nut (''Bertholletia excelsa'') is a South America South America is a continent A continent is one of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up t ...
s, are not nuts in a botanical sense. Common usage of the term often refers to any hard-walled, edible kernel as a nut. Nuts are an energy-dense and
nutrient A nutrient is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition * Matter, anything that has mass and t ...
-rich food source.


Botanical definition

A seed is the mature fertilised ovule of a plant; it consists of three parts, the
embryo An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism that consists of more than one cell (biology), cell, in contrast to a unicellular organism. All species of animals, Embryophyte, la ...

embryo
which will develop into a new plant, the
endosperm 350px, right The endosperm is a tissue produced inside the seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The ...
which contains nutrients, and a protective seed coat.
Botanically Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowledge in th ...

Botanically
, a nut is a seed which has a large proportion of endosperm and a tough seed coat which becomes increasingly hard as the nut matures. One or a few nuts may be contained in an
involucre ''). All the "leaves" in this image are bracts. In botany Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific metho ...
, a cup-shaped structure formed from the flower
bract ''). All the "leaves" in this image are bracts. In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in th ...

bract
s. The involucre may be scaly, spiny, leafy or tubular, depending on the species of nut. Most nuts come from the
pistils Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl (botany), whorl of a flower; it consists of (one or mo ...
with ''inferior'' ovaries (see
flower A flower, sometimes known as a bloom or blossom Image:Cerisier du Japon Prunus serrulata.jpg, Cherry blossoms in Paris in full bloom. In botany, blossoms are the flowers of stone fruit fruit tree, trees (genus ''Prunus'') and of some other plan ...

flower
) and all are ''indehiscent'' (not opening at maturity). True nuts are produced, for example, by some plant families of the
order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or waste, and the habit of achieving a ...
Fagales The Fagales are an order (biology), order of flowering plants, including some of the best-known trees. The order name is derived from genus ''Fagus'', beeches. They belong among the rosid group of dicotyledons. The families and genera currently ...
. These include
beech Beech (''Fagus'') is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, v ...

beech
(''Fagus''),
chestnut The chestnuts are the deciduous In the fields of horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticulturists are agriculturis ...

chestnut
(''Castanea''),
oak An oak is a tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including on ...

oak
(''Quercus''), Stone-oak,(''Lithocarpus'') and
tanoak ''Notholithocarpus densiflorus'', commonly known as the tanoak or tanbark-oak, is a broadleaf tree A broad-leaved, broad-leaf, or broadleaf tree is any tree within the diverse botanical group of angiosperms The flowering plants, also known as ...
(''Notholithocarpus'') in the family
Fagaceae Fagaceae is a family of flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 416 Family (biology), families, approximat ...
, as well as
hazel The hazel (''Corylus'') is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classificati ...

hazel
,
filbert
filbert
(''Corylus'') and
hornbeam Hornbeams are hardwood is a popular hardwood Hardwood is wood from Dicotyledon, dicot trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal ecosystem, boreal latitudes they are mostly deciduou ...
(''Carpinus'') in the family
Betulaceae Betulaceae, the birch family, includes six genera of deciduous In the fields of horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticu ...
. Also widely known as nuts are dry
drupe ), showing both fruit In botany, a fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate seeds. Edible fruits, in ...
s, which include
pecan The pecan (''Carya illinoinensis'') is a species of hickory native to the southern United States and northern Mexico in the region of the Mississippi River. The tree is cultivated for its seed in the southern United States, primarily in Georgia ...

pecan
s (''Carya illinoensis''),
almond The almond (''Prunus dulcis'', syn. ''Prunus amygdalus'') is a species of tree native to Iran Iran ( fa, ایران ), also called Persia, and officially the Islamic Republic of Iran, is a country in Western Asia Western Asia, ...

almond
s (''Prunus amygdalus''),
macadamia ''Macadamia'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer t ...

macadamia
(''Macadamia integrifolia''),
candlenut ''Aleurites moluccanus'', the candlenut, is a flowering A flower, sometimes known as a bloom or blossom, is the reproductive Reproduction (or procreation or breeding) is the biological process by which new individual organisms – ...
(''Aleurites moluccanus''),
water caltrop The water caltrop is any of three extant species of the genus ''Trapa'': ''Trapa natans'', ''Trapa bicornis'' and the endangered ''Trapa rossica''. It is also known as buffalo nut, bat nut, devil pod, ling nut, ''lin kok, ling jow'', ling kio nut ...
(''Trapa bicornis'') and
walnut A walnut is the Nut (fruit), nut of any tree of the genus ''Juglans'' (family Juglandaceae), particularly the Persian or English walnut, ''Juglans regia''. A walnut is the edible seed of a drupe, and thus not a true botanical nut. It is com ...

walnut
s (''Juglans regia''). A drupe is an
indehiscent Dehiscence is the splitting of a mature plant structure along a built-in line of weakness in order to release its contents. This is common among fruit In botany Botany, also called , plant biology or phytology, is the science of plan ...
fruit which has an outer fleshy part consisting of the
exocarp Fruit anatomy is the plant anatomy Plant anatomy or phytotomy is the general term for the study of the internal structure A structure is an arrangement and organization of interrelated elements in a material object or system A system is a ...
, or skin, and
mesocarp Fruit anatomy is the plant anatomy Plant anatomy or phytotomy is the general term for the study of the internal structure A structure is an arrangement and organization of interrelated elements in a material object or system A system is a ...
, or flesh, which surround a single pit or stone, the
endocarp Fruit anatomy is the plant anatomy Plant anatomy or phytotomy is the general term for the study of the internal structure A structure is an arrangement and organization of interrelated elements in a material object or system A system is a ...
with a
seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positi ...

seed
(kernel) inside. In a dry drupe, the outer parts dry up and the remaining husk is part of the ovary wall or
pericarp Fruit anatomy is the plant anatomy Plant anatomy or phytotomy is the general term for the study of the internal structure A structure is an arrangement and organization of interrelated elements in a material object or system A system is ...
, and the hard inner wall surrounding the seed represents the inner part of the pericarp. A small nut may be called a "nutlet" (or nucule, a term otherwise referring to the oogonium of ). In
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

botany
, the term "nutlet" specifically refers to a
pyrena A pyrena or pyrene (commonly called a "pit" or "stone") is the fruitstone within a drupe ), showing both fruit In botany, a fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after ...
or pyrene, which is a
seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positi ...

seed
covered by a stony layer, such as the kernel of a
drupe ), showing both fruit In botany, a fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate seeds. Edible fruits, in ...
. Walnuts and (
Juglandaceae The Juglandaceae are a plant family known as the walnut family. They are trees, or sometimes shrubs, in the order Fagales. Members of this family are native to the Americas, Eurasia, and Southeast Asia. The nine or ten genera in the family have a ...
) have fruits that are difficult to classify. They are considered to be nuts under some definitions but are also referred to as drupaceous nuts. In common use, a "tree nut" is, as the name implies, any nut coming from a tree. This most often comes up regarding food allergies; a person may be allergic specifically to peanuts (which are not tree nuts but
legume A legume () is a plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can ...

legume
s), whereas others may be allergic to the wider range of nuts that grow on trees.


Production

In the 21st century, some dozen nuts comprise most of worldwide production, shown in the table below for major commercial nuts.


Food and health effects

Nuts contain the diverse nutrients that are needed for the growth of a new plant. Composition varies, but they tend to have a low water and
carbohydrate A carbohydrate () is a biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a ...
content, with high levels of fats,
protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...
,
dietary minerals In the context of nutrition, a mineral is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemica ...
, and
vitamin A vitamin is an organic molecule , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's ability to Catenation, ...
s. The digestibility of the protein at about 90% is slightly lower than that of meat and fish, but can be improved by thorough chewing. The fats are largely unsaturated and nuts are a source of essential
omega-3 fatty acid Omega−3 fatty acids, also called Omega-3 oils, ω−3 fatty acids or ''n''−3 fatty acids, are polyunsaturated fatty acid Polyunsaturated fatty acids (PUFAs) are fatty acids that contain more than one double bond in their backbone. This ...
s. As part of a healthy human diet, long-term consumption of diverse nutrients in nuts may contribute to a lower risk of
cardiovascular diseases Cardiovascular disease (CVD) is a class of diseases that involve the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood car ...
, reduced levels of
blood cholesterol Blood is a body fluid Body fluids, bodily fluids, or biofluids are liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformation (mechanics), deforms (flows) under an applied shear s ...
, and lower all-cause mortality. For vegetarians and
vegans Veganism is the practice of abstaining from the use of s, particularly in , and an associated philosophy that rejects the . An individual who follows the diet or philosophy is known as a vegan. Distinctions may be made between several catego ...
, nuts provide many of the essential nutrients which may be in short supply in other
plant food A fertilizer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American En ...
s. Nuts supply nutrients for humans and wildlife. Because nuts generally have a high oil content, they are a significant energy source. Many seeds are edible by humans and used in cooking, eaten raw, sprouted, or roasted as a
Snack A snack is a small portion of food Food is any substance consumed to provide nutritional Nutrition is the biochemical Biochemistry or biological chemistry, is the study of chemical processes within and relating to living organism ...

Snack
food, ground to make nut butters, or pressed for oil that is used in cooking and cosmetics. Moderate nut consumption about per week may benefit weight control and contribute to lowering body weight in humans. Nuts used for food are a common source of food allergens. Reactions can range from mild symptoms to severe ones, a condition known as
anaphylaxis Anaphylaxis is a serious allergic reaction Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable rea ...
, which can be life-threatening. The reaction is due to the release of
histamine Histamine is an organic nitrogen Nitrogen is the chemical element with the Symbol (chemistry), symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772. Although Carl Wilhelm Scheele a ...

histamine
by the body in response to an
allergen An allergen is a type of antigen In immunology Immunology is a branch of biology that covers the study of immune systems in all organisms. Immunology charts, measures, and contextualizes the Physiology, physiological functioning of the im ...
in the nuts, causing skin and other possible reactions. Many experts suggest that a person with an allergy to peanuts should avoid eating tree nuts, and vice versa.


Nutrition


Constituents

Nuts are the source of energy and nutrients for the new plant. They contain a relatively large quantity of calories, essential unsaturated and
monounsaturated fat In nutrition Nutrition is the biochemical and physiological process by which an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies ...
s including
linoleic acid Linoleic acid is an organic compound , CH4; is among the simplest organic compounds. In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules ...

linoleic acid
and
linolenic acid Linolenic acid is a type of fatty acid fatty acids have perfectly straight chain structure. Unsaturated ones are typically bent, unless they have a trans configuration. In chemistry Chemistry is the scientific discipline involved with Ch ...
, vitamins, and essential amino acids. Many nuts are good sources of
vitamin E Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vitamin ...

vitamin E
, vitamin B2,
folate Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...
,
fiber Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including ...
, and essential minerals, such as magnesium, phosphorus, potassium, copper, and selenium. This table lists the percentage of various nutrients in four unroasted seeds.


Research

Nuts are under preliminary research to assess whether their consumption may lower risk for some diseases, such as
cardiovascular diseases Cardiovascular disease (CVD) is a class of diseases that involve the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood car ...
and cancer. A 2014 review indicated that consuming one or more servings of nuts or
peanut butter Peanut butter is a food Paste (food), paste or Spread (food), spread made from Grinding (abrasive cutting), ground, dry roasting, dry-roasted peanuts. It commonly contains additional ingredients that modify the taste or texture, such as salt, s ...
per day could lower the risk of
ischemic heart disease Coronary artery disease (CAD), also called coronary heart disease (CHD), Ischemia, ischemic heart disease (IHD), or simply heart disease, involves the reduction of blood flow to the myocardium, heart muscle due to build-up of plaque (atherosclero ...
, overall cardiovascular disease, stroke in women, and all-cause
mortality Mortality is the state of being mortal, or susceptible to death (1906) Death is the permanent, Irreversible process, irreversible cessation of all biological process, biological functions that sustain a living organism. Brain death is some ...
.


See also

* *
List of culinary nuts A culinary nut is a dry, edible fruit In botany, a fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate seed ...
*
List of edible seeds An edible seed is a that is suitable for or consumption. Of the six major plant parts, seeds are the dominant source of human s and . A wide variety of plant provide edible seeds; most are s, while a few are s. As a global food source, the mos ...
*
List of foods This is a categorically-organized list of foods. Food Food is any substance consumed to provide nutritional support for an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any ind ...
*
Nutmeg Nutmeg is the seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was relea ...

Nutmeg
*
Achene An achene (; Greek ἀ, ''a'', privative + χαίνειν, ''chainein'', to gape; also sometimes called akene and occasionally achenium or achenocarp) is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarp ...

Achene


Notes


References

Further reading *Albala, Ken (2014) ''Nuts A Global History''. The Edible Series.


External links

* {{Authority control Fruit morphology Snack foods Vegan cuisine Vegetarian cuisine Christmas food Staple foods Types of food