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 are called nuts, but in a botanical context, "nut" implies that the shell does not open to release the seed (indehiscent).
Most seeds come from fruits that naturally free themselves from the shell, but this is not the case in nuts such as , , and , which have hard shell walls and originate from a compound ovary.
Definition
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.
Botany, 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
. The involucre may be scaly, spiny, leafy or tubular, depending on the species of nut.
Most nuts come from the
carpel 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),
Lithocarpus (
Lithocarpus) and
Notholithocarpus (
Notholithocarpus) in the family
Fagaceae, as well as
hazel,
Corylus maxima (
Corylus) and
hornbeam (
Carpinus) in the family
Betulaceae.
A small nut may be called a "nutlet" (formerly called a nucule,[E.g., ; compare The term nucula was applied specifically to hazelnuts ( Corylus) in ] a term otherwise referring to the oogonium of Charales
Toxicity
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, 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.
Tree nut allergies are distinct from
peanut allergy, as
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.
Consumption as food
For
wildlife and humans, nuts supply a relatively large quantity of
from
, such as
linoleic acid and
linolenic acid, and monounsaturated fats.
[ Nuts are rich sources of B vitamins, vitamin E, and essential amino acids.][
]
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.
Many nuts and seeds are edible and used in cooking, eaten raw, sprouted, or roasted as a Snack, soaked in water and filtered to make Plant milk, ground to make nut butters, or pressed for oil that is used in cooking and cosmetics.
See also
Further reading
-
Albala, Ken (2014) Nuts A Global History. The Edible Series.
