Nut is a general term for the large, dry, oily
seedsA seed , referred to as a kernel in some plants, is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
or
fruitThe term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. Fruits are the means by which flowering plants disseminate seeds, and the presence of seeds indicates that a structure is most likely a fruit, though not all seeds come from...
of some
plantsPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be
true nuts. Nuts are an important source of nutrients for both humans and wildlife.
A nut is a type of seed. Nuts are both the seed and the fruit, and cannot be separated.
Nut is a general term for the large, dry, oily
seedsA seed , referred to as a kernel in some plants, is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
or
fruitThe term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. Fruits are the means by which flowering plants disseminate seeds, and the presence of seeds indicates that a structure is most likely a fruit, though not all seeds come from...
of some
plantsPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be
true nuts. Nuts are an important source of nutrients for both humans and wildlife.
A nut is a type of seed. Nuts are both the seed and the fruit, and cannot be separated. Seeds come from fruit, and can be removed from the fruit, like
almondsThe Almond is a species of tree native to the Middle East. Almond is also the name of the edible and widely cultivated nut of this tree...
,
cashewsThe cashew is a tree in the flowering plant family Anacardiaceae. The plant is native to northeastern Brazil. Its English name derives from the Portuguese name for the fruit of the cashew tree, caju, which in turn derives from the indigenous Tupi name, acajú...
and
walnutsWalnuts are plants in the family Juglandaceae. They are deciduous trees, 10–40 meters tall , with pinnate leaves 200–900 millimetres long , with 5–25 leaflets; the shoots have chambered pith, a character shared with the wingnuts but not the hickories in the same family.The 21 species...
which have to be extracted from the fruit. Some nuts as defined in culinary usage like
pistachiosThe pistachio is a small tree native to mountainous regions of Greece, Syria, Iran, Kyrgyzstan, Turkmenistan, Turkey and western Afghanistan, that produces an important culinary nut. Pistacia vera often is confused with other species in the genus Pistacia that are also known as pistachio...
, are not true nuts in a biological sense.
The grouping of many similar dry seeds and fruits under the single generic name "nut" is not followed in many other languages, which have only individual names for each type.
Botanical definition
A nut in
botanyBotany, plant science, phytology, or plant biology is a branch of biology and is the scientific study of plant life and development...
is a simple dry
fruitThe term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. Fruits are the means by which flowering plants disseminate seeds, and the presence of seeds indicates that a structure is most likely a fruit, though not all seeds come from...
with one
seedA seed , referred to as a kernel in some plants, is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
(rarely two) in which the
ovaryIn the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. Specifically, it is the part of the carpel which holds the ovule and is located above or below or at the point of connection with the base of the petals and sepals...
wall becomes very hard (stony or woody) at maturity, and where the seed remains unattached or unfused with the ovary wall. Most nuts come from the pistils with
inferior ovaries (see
flowerA flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds...
) and all are
indehiscent (not opening at maturity). True nuts are produced, for example, by some plant families of the
orderIn scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
FagalesThe Fagales are an 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...
.
Order Fagales
- Family Fagaceae
The family Fagaceae, or beech family, comprises about 900 species of both evergreen and deciduous trees and shrubs, which are characterized by alternate simple leaves with pinnate venation, unisexual flowers in the form of catkins, and fruit in the form of cup-like nuts. Fagaceous leaves are often...
- Chestnut
Chestnut is a genus of eight or nine species of deciduous trees and shrubs in the beech family Fagaceae, native to temperate regions of the Northern Hemisphere. The name also refers to the edible nuts they produce.-Species:The Chestnut belongs to the same Fagaceae family as the Oak and Beech...
(Castanea)
- Beech
Beech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.The leaves of beech trees are entire or sparsely toothed, from 5–15 cm long and 4–10 cm broad...
(Fagus)
- Oak
An oak is a tree or shrub in the genus Quercus , of which about 400 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
(Quercus)
- Stone-oak
Lithocarpus is a genus in the beech family Fagaceae, differing from Quercus in the erect male spikes. The Kew Checklist accepts 334 species, though some other texts suggest as low as 100 species. About 100 Asian species of the genus were formerly treated in the genus Pasania. All but one are...
, TanoakLithocarpus densiflorus, commonly known as the Tanoak or Tanbark-oak, is an evergreen tree in the beech family Fagaceae, native to the western United States, in California as far south as the Transverse Ranges and north to southwest Oregon...
(Lithocarpus)
- Family Betulaceae
Betulaceae, or the Birch Family, includes six genera of deciduous nut-bearing trees and shrubs, including the birches, alders, hazels, hornbeams and hop-hornbeams, numbering about 130 species...
- Alder
Alder is the common name of a genus of flowering plants belonging to the birch family . The genus comprises about 30 species of monoecious trees and shrubs, few reaching large size, distributed throughout the North Temperate Zone and in the Americas also along the Andes southwards to...
(Alnus)
- Hazel
The hazels are a genus of deciduous trees and large shrubs native to the temperate northern hemisphere. The genus is usually placed in the birch family Betulaceae, though some botanists split the hazels into a separate family Corylaceae.They have simple, rounded leaves with double-serrate margins...
, Filbert (Corylus)
- Hornbeam
Plants in the genus Carpinus are commonly called Hornbeams. They are relatively small hardwood trees. Many botanists place the hornbeams in the birch family Betulaceae, though some group them with the hazels and hop-hornbeams in a segregate family, Corylaceae...
Culinary definition and uses
A nut in
cuisineCuisine is a specific set of cooking traditions and practices, often associated with a specific culture. It is often named after the region or place where its underlining culture is present...
is a much less restrictive category than a nut in botany, as the term is applied to many
seedA seed , referred to as a kernel in some plants, is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s that are not botanically true nuts. Any large, oily kernel found within a shell and used in food may be regarded as a nut. Pistachios are seeds enclosed in a tough fruit, which does not split open enough to release the seeds.
Because nuts generally have a high oil content, they are a highly prized food and energy source. A large number of seeds are edible by humans and used in cooking, eaten raw, sprouted, or roasted as a
snack foodA snack food is seen in Western culture as a type of food not meant to be eaten as a main meal of the day – breakfast, lunch, or dinner – but one rather that is intended to assuage a person's hunger between these meals, providing a brief supply of energy for the body...
, or pressed for oil that is used in cookery and
cosmeticsCosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, permanent waves, colored contact lenses, hair colors, [hair sprays] and gels,...
. Nuts (or seeds generally) are also a significant source of nutrition for wildlife. This is particularly true in temperate climates where animals such as
jayThe jays are several species of medium-sized, usually colorful and noisy, passerine birds in the crow family Corvidae. The names jay and magpie are somewhat interchangeable, and the evolutionary relationships are rather complex...
s and
squirrelA squirrel is one of many small or medium-sized rodents in the family Sciuridae. In the English-speaking world, squirrel commonly refers to members of this family's genera Sciurus and Tamiasciurus, which are tree squirrels with large bushy tails, indigenous to Asia, the Americas and Europe....
s store
acornThe acorn, or oak nut, is the nut of the oak tree . It usually contains a single seed , enclosed in a tough, leathery shell, and borne in a cup-shaped cupule. Acorns vary from 1–6 cm long and 0.8–4 cm broad...
s and other nuts during the autumn to keep them from starving during the late autumn, all of winter, and early spring.
Nuts, including both tree nuts and
peanutThe peanut, or groundnut , is a species in the legume family native to South America, Mexico and Central America. It is an annual herbaceous plant growing 30 to 50 cm tall...
s (not a nut but rather a
legumeIn botanical writing legume is a plant in the family Fabaceae , or a fruit of these specific plants. A'legume' fruit is a simple dry fruit that develops from a simple carpel and usually dehisces on two sides. A common name for this type of fruit is a pod, although "pod" is also applied to a few...
), are among the most common
food allergensA food allergy is an adverse immune response to a food protein. Food allergy is distinct from other adverse responses to food, such as food intolerance, pharmacologic reactions, and toxin-mediated reactions....
.
Some fruits and seeds that are nuts in the culinary sense:
- Almond
The Almond is a species of tree native to the Middle East. Almond is also the name of the edible and widely cultivated nut of this tree...
s and walnutWalnuts are plants in the family Juglandaceae. They are deciduous trees, 10–40 meters tall , with pinnate leaves 200–900 millimetres long , with 5–25 leaflets; the shoots have chambered pith, a character shared with the wingnuts but not the hickories in the same family.The 21 species...
s are the edible seeds of drupeIn botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...
fruits — the leathery "flesh" is removed at harvest.
- Brazil nut
The Brazil nut is a South American tree in the family Lecythidaceae, and also the name of the tree's commercially harvested edible seed....
is the seed from a capsuleIn botany a capsule is a type of simple, dry fruit produced by many species of flowering plants. A capsule is a dehiscent structure composed of two or more carpels, that, at maturity, split apart to release the seeds within...
.
- Candlenut
The Candlenut , is a flowering tree in the spurge family, Euphorbiaceae, also known as Candleberry, Indian walnut, Kemiri, Varnish tree or Kukui nut tree....
(used for oil) is a seed.
- Cashew
The cashew is a tree in the flowering plant family Anacardiaceae. The plant is native to northeastern Brazil. Its English name derives from the Portuguese name for the fruit of the cashew tree, caju, which in turn derives from the indigenous Tupi name, acajú...
nut is a seed.
- Coconut
The Coconut Palm is a member of the family Arecaceae . It is the only species in the genus Cocos, and is a large palm, growing to 30 m tall, with pinnate leaves 4–6 m long, pinnae 60–90 cm long; old leaves break away cleanly leaving the trunk smooth. The term coconut refers to the seed of the...
is a dry, fibrous drupeIn botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...
.
- Gevuinanut
- Horse-chestnut
The genus Aesculus comprises 13-19 species of woody trees and shrubs native to the temperate northern hemisphere, with 6 species native to North America and 7-13 species native to Eurasia; there are also several hybrids. Species are deciduous or evergreen...
is an inedible capsule.
- Macadamia
Macadamia is a genus of nine species of flowering plants in the family Proteaceae, with a disjunct distribution native to eastern Australia , New Caledonia and Sulawesi in Indonesia ....
nut is a creamy white kernel (Macadamia integrifoliaMacadamia integrifolia is a tree in the Proteaceae family, native to New South Wales and Queensland in Australia. Common names include Macadamia Nut, Poppel Nut, Bauple Nut, Bopple Nut, Queensland Nut or Nut Oak....
).
- Malabar chestnut
Pachira aquatica is a tropical wetland tree native to Central and South America where it grows in swamps. It is known by the common names Malabar chestnut, Guiana chestnut, provision tree, saba nut, and is commercially sold under the name money tree and money plant.-Characteristics:Pachira aquatica...
- Mongongo
Formerly known as Ricinodendron rautanenii, the mongongo tree is a member of the family Euphorbiaceae and of the monotypic genus Schinziophyton. A large, spreading tree, the mongongo reaches 15-20 metres tall. It is found on wooded hills and amongst sand dunes, and is associated with the...
- Peanut
The peanut, or groundnut , is a species in the legume family native to South America, Mexico and Central America. It is an annual herbaceous plant growing 30 to 50 cm tall...
is a legumeIn botanical writing legume is a plant in the family Fabaceae , or a fruit of these specific plants. A'legume' fruit is a simple dry fruit that develops from a simple carpel and usually dehisces on two sides. A common name for this type of fruit is a pod, although "pod" is also applied to a few...
and a seed and not a nut at all.
- Pine nut
Pine nuts are the edible seeds of pines . About 20 species of pine produce seeds large enough to be worth harvesting; in other pines the seeds are also edible, but are too small to be of great value as a human food....
is the seed of several species of pinePines are coniferous trees in the genus Pinus , in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Distribution:...
(coniferousThe conifers, division Pinophyta, also known as division Coniferophyta or Coniferae, are one of 13 or 14 division level taxa within the Kingdom Plantae. Pinophytes are gymnosperms. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority...
trees).
- Pistachio
The pistachio is a small tree native to mountainous regions of Greece, Syria, Iran, Kyrgyzstan, Turkmenistan, Turkey and western Afghanistan, that produces an important culinary nut. Pistacia vera often is confused with other species in the genus Pistacia that are also known as pistachio...
nut is the seed of a thin-shelled drupe.
Nutritional benefits
Several epidemiological studies have revealed that people who consume nuts regularly are less likely to suffer from
coronary heart diseaseCoronary artery disease is the end result of the accumulation of atheromatous plaques within the walls of the coronary arteries that supply the myocardium with oxygen and nutrients...
. Recent
clinical trialClinical trials are conducted to allow safety and efficacy data to be collected for new drugs or devices. These trials can only take place once satisfactory information has been gathered on the quality of the product and its non-clinical safety, and Health Authority/Ethics Committee approval is...
s have found that consumption of various nuts such as
almondThe Almond is a species of tree native to the Middle East. Almond is also the name of the edible and widely cultivated nut of this tree...
s and
walnutWalnuts are plants in the family Juglandaceae. They are deciduous trees, 10–40 meters tall , with pinnate leaves 200–900 millimetres long , with 5–25 leaflets; the shoots have chambered pith, a character shared with the wingnuts but not the hickories in the same family.The 21 species...
s can lower serum LDL cholesterol concentrations. Although nuts contain various substances thought to possess cardioprotective effects, scientists believe that their Omega 3
fatty acidIn chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail , which is either saturated or unsaturated...
profile is at least in part responsible for the hypolipidemic response observed in clinical trials.
In addition to possessing cardioprotective effects, nuts generally have a very low
glycemic indexThe glycemic index, glycaemic index, or GI is a measure of the effects of carbohydrates on blood sugar levels. Carbohydrates that break down quickly during digestion, releasing glucose rapidly into the bloodstream, have a high GI; carbohydrates that break down more slowly, releasing glucose more...
(GI).
Consequently, dietitians frequently recommend nuts be included in diets prescribed for patients with
insulin resistanceInsulin resistance is the condition in which normal amounts of insulin are inadequate to produce a normal insulin response from fat, muscle and liver cells. Insulin resistance in fat cells reduces the effects of insulin and results in elevated hydrolysis of stored triglycerides in the absence of...
problems such as
diabetes mellitus type 2Diabetes mellitus type 2 or type 2 diabetes is a disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency...
.
One study found that people who eat nuts live two to three years longer than those who do not. However, this may be because people who eat nuts tend to eat less
junk foodJunk food is an informal term applied to some foods which are perceived to have little or no nutritional value, or to products with nutritional value but which also have ingredients considered unhealthy when regularly eaten, or to those considered unhealthy to consume at all...
.
Nuts contain the all important fatty acids, linoleic and linolenic acids, which are critical for growth, physical and mental development, healthy hair and skin, blood pressure control, immunological responses and blood clotting. In addition, the fats in nuts for the most part are unsaturated fats, particularly monounsaturated fats. This type does not elevate blood cholesterol levels like saturated fats.
Furthermore nuts supply one of the best natural sources of vitamins E, F, and G (docopherol, an antioxidant), and are rich in protein, folate, fiber, and essential minerals such as magnesium, phosphorus, potassium, copper, and selenium.
Other uses
The nut of the horse-chestnut tree (
Aesculus species, especially
Aesculus hippocastanum), is called a
conker in the
British IslesThe British Isles are a group of islands off the northwest coast of continental Europe that include Great Britain, Ireland and numerous smaller islands. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland, and Ireland...
. Conkers are inedible because they contain toxic
glucosideA glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes....
aesculinAesculin is a glucoside that naturally occurs in the horse chestnut , California Buckeye and in daphnin .-Medical uses:...
. They are used in a popular children's game, known as
conkers, where the nuts are threaded onto a strong cord and then each contestant attempts to break his opponent's conker by hitting it with his own. Horse chestnuts are also popular
slingshotA slingshot is a small hand-powered projectile weapon. The forked Y-shaped frame has two rubber strips attached to the uprights, leading back to a pocket for holding the projectile.It is normally fired by holding the frame in the non-dominant hand, extended at arms length...
ammunition.
A related species,
Aesculus californicaAesculus californica is a species of buckeye endemic to California, and the only buckeye native to the state....
, was eaten by the
Native AmericansNative Americans in the United States is the phrase that describes indigenous peoples from North America now encompassed by the continental United States, including parts of Alaska and the island state of Hawaii. They comprise a large number of distinct tribes, states, and ethnic groups, many of...
of
CaliforniaCalifornia is the most populous state in the United States, and the third largest by area. California is the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil...
during famines after the toxic constituents were leached out.
External links