Encyclopedia
The term
fruit has different meanings depending on context. In
botany, a fruit is the
ripened
ovary—together with
seeds—of a
flowering plant. In many species, the fruit incorporates the ripened ovary and surrounding tissues. Fruits are the means by which flowering plants disseminate seeds. In
cuisine, when discussing fruit as
food, the term usually refers to just those
plant fruits that are sweet and fleshy, examples of which include
plum,
apple and orange. However, a great many common
vegetables, as well as nuts and
grains, are the fruit of the plant species they come from.
No one terminology really fits the enormous variety that is found among plant fruits. Botanical terminology for fruits is inexact and will remain so. The term
false fruit is sometimes applied to a fruit like the
fig or to a plant structure that resembles a fruit but is not derived from a flower or flowers. Some
gymnosperms, such as
yew, have fleshy
arils that resemble fruits and some
junipers have
berry-like, fleshy cones. The term "fruit" has also been inaccurately applied to the seed-containing female
cones of many
conifers.
With most fruits
pollination is a vital part of fruit culture, and the lack of knowledge of
pollinators and pollenizers can contribute to poor crops or poor quality crops. In a few species, the fruit may develop in the absence of pollination/fertilization, a process known as
parthenocarpy. Such fruits are seedless. A plant that does not produce fruit is known as
acarpous, meaning "without fruit".
Botanic fruit and culinary fruit
Many foods are botanically fruit but are treated as
vegetables in cooking. These include
cucurbits ,
tomato,
aubergine , and sweet
pepper and some
spices, such as
allspice and
chillies. In the commercial world,
European Union rules define
carrot as a fruit for the purposes of measuring the proportion of "fruit" contained in carrot jam. In the culinary sense, a fruit is usually any sweet tasting plant product associated with seed, a vegetable is any savoury or less sweet plant product, and a nut any hard, oily, and shelled plant product.
Although a nut is a type of fruit, it is also a popular term for edible seeds, such as
peanut,
pistachio and
walnut. Technically, a
cereal grain is a fruit termed a
caryopsis. However, the fruit wall is very thin and fused to the seed coat so almost all of the edible grain is actually a
seed. Therefore, cereal grains, such as
corn,
wheat and
rice are better considered edible seeds, although some references list them as fruits. Edible gymnosperms seeds are often misleadingly given fruit names, e.g.
pine nuts,
ginkgo nuts, and
juniper berries.
Fruit development
A fruit is a ripened ovary. After the
ovule in an ovary is
fertilized in a process known as
pollination, the ovary begins to ripen. The
ovule develops into a
seed and the ovary wall
pericarp may become fleshy or only form a hard outer covering . In some cases, the sepals,
petals and/or stamens and style of the
flower fall off. Fruit development continues until the seeds have matured. With some multiseeded fruits the extent to which the flesh develops is proportional to the number of fertilized ovules.
The wall of the fruit, developed from the ovary wall of the flower, is called the
pericarp. The
pericarp is often differentiated into two or three distinct layers called the
exocarp ,
mesocarp , and
endocarp . In some fruits, especially simple fruits derived from an
inferior ovary, other parts of the flower , fuse with the ovary and
ripen with it. The plant hormone
Ethylene causes ripening. When such other floral parts are a significant part of the fruit, it is called an
accessory fruit. Since other parts of the flower may contribute to the structure of the fruit, it is important to study flower structure to understand how a particular fruit forms. An example is the
raspberry, whose simple fruits are termed
drupelets because each is like a small
drupe attached to the receptacle. In some
bramble fruits the receptacle is elongate and part of the ripe fruit, making the blackberry an
aggregate-accessory fruit. The
strawberry is also an aggregate-accessory fruit, only one in which the seeds are contained in
achenes. In all these examples, the fruit develops from a single flower with numerous pistils.
Multiple fruit
A
multiple fruit is one formed from a cluster of flowers . Each flower produces a fruit, but these mature into a single mass. Examples are the
pineapple, edible
fig,
mulberry,
osage-orange, and
breadfruit.
In the photograph on the right, stages of flowering and fruit development in the
noni or Indian mulberry can be observed on a single branch. First an inflorescence of white flowers called a
head is produced. After
fertilization, each flower develops into a
drupe, and as the drupes expand, they become
connate into a
multiple fleshy fruit called a
syncarpet.
There are also many dry multiple fruits, e.g.
Seedless fruits
Seedlessness is an important feature of some fruits of commerce. Commercial
cultivars of
bananas and
pineapples are examples of seedless fruits. Some cultivars of
citrus fruits , table
grapes,
grapefruit, and
watermelons are valued for their seedlessness. In some species, seedlessness is the result of
parthenocarpy, where fruits set without fertilization. Parthenocarpic fruit set may or may not require pollination. Most seedless citrus fruits require a pollination stimulus; bananas and pineapples do not. Seedlessness in table grapes results from the abortion of the
embryonic plant that is produced by fertilization, a phenomenon known as
stenospermocarpy which requires normal pollination and fertilization.
The sweet flesh of many fruits is "deliberately" appealing to animals, so that the seeds held within are eaten and "unwittingly" carried away and deposited at a distance from the parent. Likewise, the nutritious, oily kernels of nuts are appealing to rodents who hoard them in the soil in order to avoid starving during the winter, thus giving those seeds that remain uneaten the chance to
germinate and grow into a new plant away from their parent.
Olive fruit is pressed for
olive oil.
Apples are often used to make
vinegar. The spices
vanilla,
paprika,
allspice and
black pepper are made from fruits.
Nonfood uses
Because fruits have been such a major part of the human diet, different cultures have developed many different uses for various fruits that do not depend on them being edible. Many dry fruits are used as decorations or in dried flower arrangements, such as
unicorn plant,
lotus,
wheat,
annual honesty and
milkweed. Ornamental
trees and
shrubs are often cultivated for their colorful fruits, including
holly,
pyracantha,
viburnum,
skimmia,
beautyberry and
cotoneaster.
Fruits of
opium poppy are the source of the drugs
opium and
morphine.
Osage orange fruits are used to repel
cockroaches.
Bayberry fruits provide a wax often used to make candles. Many fruits provide natural dyes, e.g.
walnut,
sumac,
cherry and
mulberry. Dried
gourds are used as decorations, water jugs, bird houses, musical instruments, cups and dishes.
Pumpkins are carved into
Jack-o'-lanterns for
Halloween. The spiny fruit of
burdock or cocklebur were the inspiration for the invention of
Velcro.
Coir is a fiber from the fruit of
coconut that is used for doormats, brushes, mattresses, floortiles, sacking, insulation and as a growing medium for container plants. The shell of the coconut fruit is used to make souvenir heads, cups, bowls, musical instruments and bird houses.
Notes
External links
- at bioimages.vanderbilt.edu
- at bioimages.vanderbilt.edu
- from Bouquet of Fruits
- from California Rare Fruit Growers, Inc.
- from Hawaii
- from Poland
See also
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