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Nut (fruit)

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In common language, we often call many dry seeds "nuts." However, the botanical definition is much more specific. A true nut is a type of fruit with a hard or tough nutshell. This shell protects a kernel, which is the edible part inside.

Botanically, a nut is a fruit with a woody pericarp. This pericarp develops from a syncarpous gynoecium. One key feature of a true nut is that it is indehiscent. This means the shell does not open to release the seed when it is mature. Most other seeds come from fruits that naturally free themselves from their shells.

4 walnut kernels
4 walnut kernels

To understand a nut, we must look at the anatomy of the seed. A seed is a mature, fertilized ovule of a plant. It consists of three distinct parts. First, there is the embryo, which will eventually grow into a new plant. Second, the seed contains stored food for that embryo to use. Third, it has a protective seed coat to keep the embryo safe.

Some nuts also grow within an involucre. An involucre is a cup-shaped structure formed from flower bracts. Depending on the species, an involucre might be scaly, spiny, leafy, or tubular.

Different plant families produce various types of nuts. True nuts are produced by plants in the order Fagales. For example, the family Fagaceae includes beech, chestnut, oak, stone-oak, and tanoak. Another group is the family Betulaceae. This family includes hazel, filbert, and hornbeam.

4 walnut kernels
4 walnut kernels

Some fruits are harder to classify into these strict groups. Walnuts and hickories, such as pecans, belong to the family Juglandaceae. These are often called drupaceous nuts. If a nut is very small, it may be called a nutlet. In botany, the term nutlet can also describe a pyrene. A pyrene is a seed covered by a stony layer, like the kernel found in a drupe.

Nuts are highly nutritious for both humans and wildlife. They provide a large amount of calories from fats. These include monounsaturated fats and unsaturated fats like linoleic acid and linolenic acid.

Très serré
Très serré

Nuts are also rich in B vitamins and vitamin E. They provide essential amino acids for healthy growth. Most nuts have high levels of protein, dietary minerals, and dietary fiber. They generally have low water and carbohydrate content. This makes them a very dense source of energy.

Humans use nuts in many different ways in our daily lives. We can eat them raw, sprouted, or roasted as a snack. Some people soak nuts in water and then filter them to make nut milk. We can also grind them into various nut butters. Another common use is pressing the nuts to create oil. This oil is used in both cooking and cosmetics.

4 walnut kernels
4 walnut kernels

While nuts are healthy, they can be dangerous for some people. Nuts are a common source of food allergens. When someone is allergic, their body releases histamine in response to the allergen. This can cause skin reactions or other symptoms. In some cases, the reaction can be severe. This life-threatening condition is known as anaphylaxis.

Très serré
Très serré

It is important to note that tree nut allergies are distinct from peanut allergies. Peanuts are actually legumes, not tree nuts. However, experts suggest that people with peanut allergies should avoid tree nuts as well.

Understanding the difference between a culinary nut and a botanical nut helps us study plant biology. It shows how scientists categorize the world based on how plants grow and reproduce. Whether it is an acorn from an oak or a hazelnut from a shrub, these fruits play a vital role in ecosystems. They provide essential energy for animals and important resources for human nutrition.

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