Fruit, the seed-bearing structure of a flowering plant. Most people think of fruits as sweet, flavorful plant parts such as apples, oranges, cherries, and strawberries. Such foods as corn, beans, or peas are termed vegetables. To a botanist, however, any ripened ovary is a fruitincluding a kernel of corn, a pod of peas, and a bean, as well as an apple, orange, cherry, or strawberry. Botanically, nuts, cockleburs, wheat grains, and cucumbers are also fruits.The orange is a succulent round citrus fruit popular for its juice.
The fruit consists of an enlarged, matured ovary. (In some cases, the fruit includes other flower or stem parts that are attached to or surround the matured ovary.) Before the ovary of a flower matures, it contains one or more ovules (immature seeds). Each ovule contains an egg cell. After an egg cell is fertilized by pollen, the ovule develops into a seed. The ovary then matures into a fruit.
Fruit protects the seeds from heat, cold, and drought. Many fruits also help to disperse the seeds. For example, the fruits of the violet and witch hazel open explosively and throw the seeds for some distance. The winged fruits of elm and maple trees are carried by the wind, and sticky berries are carried away on the feet of birds and other animals. Cockleburs and other hooked and barbed fruits catch in the hair of animals, which often take them far from the parent plants.
Dried beans and other leguminous fruits, cereal grains, and some nuts are rich in proteins, but the proteins are not as nutritious as those of meat. Avocados, nuts, and olives are rich in fat. In general, however, fruits are low in proteins and fat. Some dried fruits, such as figs and dates, are rich in carbohydrates (sugar and starch). Most fresh fruits consist of about 80 per cent water, but carbohydrates make up much of the remaining 20 per cent.
Fresh fruits are important in the diet chiefly for their minerals and vitamins, and for their laxative effect. Most fresh fruits contain iron, calcium, and vitamin C in useful quantities. Citrus fruits and tomatoes are excellent sources of vitamin C, and yellow fruits contain valuable quantities of vitamin A. Many fresh fruits contain acids that promote bowel movements, and they provide roughage (dietary fiber) that aids in elimination.
In the United States, fruit is grown commercially chiefly on the Pacific and Gulf coasts and in the Great Lakes region. (For countries and states that lead in the growing of specific fruits, see articles dealing with those fruits.) Fruits are marketed fresh, frozen, canned, and dried, and in jellies, jams, preserves, and juices.
Many fruits, especially oranges and apples, have been improved in size and flavor through selective breeding. Botanists have developed seedless varieties, such as the navel orange. Some new fruits have been created by crossbreeding; the plumcot (plum and apricot), developed by Luther Burbank, is an example.
There are four basic types of fruitssimple, aggregate, multiple, and accessory.
A simple fruit is one that develops from a single ovary. Simple fruits may be fleshy or dry.
All or most of the pericarp (the thickened wall surrounding the seed or seeds) is soft and fleshy when mature. Fleshy portions are generally called the pulp. There are two basic types of fleshy fruitsthe berry and the drupe.
1. BerryThe entire pericarp, with the exception in some cases of the rind, becomes fleshy. The seeds are embedded in the pulp. Many of the fruits called berries, such as the strawberry or raspberry, are not, botanically speaking, berries and therefore do not fall into this category.
A pepo is a berry with a hard rind.
A hesperidium is a berry with a spongy rind and segmented pulp.
2. DrupeThe seed or seeds are contained within a hard pit, or stone, in the fruit's center.
The entire wall becomes dry, sometimes brittle, at maturity. Dry fruits are classed as dehiscent or indehiscent.
1. DehiscentThe fruit splits open when ripe. There are four types:
- Legume, a many-seeded pod that splits along two seams.
- Follicle, a pod that splits along one side only.
- Capsule, a fruit containing two or more seed compartments. Capsules usually split lengthwise, but some divide into cuplike segments.
- Silique, a long, slender pod that splits along two sides when mature, exposing a paperlike interior.
2. IndehiscentThe fruit does not split open when ripe. There are five types:
- Achene, a small, one-seeded fruit with a thin, distinct wall.
- Caryopsis, or Grain, a one-seeded fruit in which the outer husk is tightly attached to the entire seed.
- Samara, a winged, one- or two-seeded fruit.
- Schizocarp, a two-seeded fruit that separates at maturity.
- Nut, a one-seeded fruit with a hard, woody shell. Many fruits commonly called nuts do not fit this description and are therefore classed in other categories. The peanut, for example, is a legume, and almonds, coconuts, and walnuts are drupes.
An aggregate fruit is one consisting of many ripened ovaries produced by a single flower. The individual ovaries may take any of the forms of simple fruits, such as drupes, achenes, etc.
This type of fruit consists of a cluster of ovaries from different flowers on a common base.
Accessory fruits contain a matured ovary, but consist mainly of tissues other than the ovary, such as other flower and stem parts. Apples, pears, and strawberries are examples of accessory fruits. In apples and pears, the ovary is surrounded by an enlarged, fleshy receptacle (an outgrowth of the stalk). These fruits are also called pomes. The strawberry consists of many small achenes on an enlarged, fleshy receptacle.