Nut is a hard shelled fruit of some plants that has an indehiscent seed. 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.

Nuts are a composite of the seed and the fruit, where the fruit does not open to release the seed. Most seeds come from fruits, and the seeds are free of the fruit, unlike nuts like hazelnuts, hickories, chestnuts and acorns, which have a stony fruit wall and originate from a compound ovary. Culinary usage of the term is less restrictive, and some nuts as defined in food preparation, like pistachios and Brazil nuts, are not nuts in a biological sense. Everyday common usage of the term often refers to any hard walled, edible kernel, as a nut.

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 botany is a simple dry fruit with one seed (rarely two) in which the ovary wall becomes very hard (stony or woody) at maturity, and where the seed remains attached or fused with the ovary wall. 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.

Culinary definition and uses

A nut in cuisine is a much less restrictive category than a nut in botany, as the term is applied to many seeds 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 do 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 food, or pressed for oil that is used in cookery and cosmetics.

Nuts used for food, whether true nut or not, are among the most common food allergens.

Some fruits and seeds that do not meet the botanical definition but are nuts in the culinary sense:

• Almonds and walnuts are the edible seeds of drupe fruits — the leathery "flesh" is removed at harvest.
• Brazil nut is the seed from a capsule.
• Candlenut (used for oil) is a seed.
• Cashew nut is a seed.
• Coconut is a dry, fibrous drupe.
• Gevuinanut
• Horse-chestnut is an inedible capsule.
• Macadamia nut is a creamy white kernel (Macadamia integrifolia).
• Malabar chestnut
• Mongongo
• Peanut is a seed.
• Pine nut is the seed of several species of pine (coniferous trees).
• Pistachio nut is the seed of a thin-shelled drupe.

Read More in Wikipedia ("Nut_(fruit)") »  

See also "List of Edible Seeds."