What is a Fruit?
A seed-bearing structure found in flowering plants or also called angiosperms is known as fruit. It is formed from the ovary present in the seed after flowering in a plant takes place. Angiosperms disseminate seeds with the help of fruits. Many edible fruits are propagated with the help of animals and humans as they help in seed dispersal; fruits are therefore in symbiotic relationship with organisms as they provide nutrition to them and in return get dispersed for new offsprings. Fruits have great agricultural output and some of these have acquired symbolic and cultural significance too.
How is a Fruit Identified?
Fruit is normally associated with the fleshy seed-associated plant structures which are sweet or sour and are usually edible in the raw state. Some of the examples include bananas, apples, grapes, lemons, strawberries and oranges. In botanical terms, fruits are often also associated with other structures namely corn kernels, bean pods, wheat grains and tomatoes. In culinary terms a fruit is defined as a sweet-tasting part of the plant and botanically, a fruit is the ripened carpel or ovary containing the seeds. An important point to be noted is that a nut is a type of fruit and many people might get confused considering it a seed whereas a seed is a ripened ovule.
So, botanically, fruits may include cucumber, squash, eggplant, legumes, like peas, peanuts, brans, chili pepper, sweet paper, etc. Also, a cereal grain like wheat, rice and corn is also a type of fruit known as caryopsis. However, later the fruit wall, being very thin, gets fused to the seed coat and leaves the edible grain which is actually a seed
Fruit Structure
A fruit consists of an important structural component called pericarp.
Pericarp: It is the outer layer which is often edible and is formed from the ovary and it surrounds the seeds. In some species, in addition to this portion, other tissues can form the edible portion as well. The pericarp, further, consists of the following structures:
Epicarp: It is the outermost layer of pericarp.
Mesocarp: It is the middle layer of pericarp.
Endocarp: It is the innermost layer of pericarp.
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Development of a Fruit
The maturation of one or more flowers results in the formation of a fruit and it is the gynoecium of the flower that forms all or some part of the fruit. Let’s discuss the development of a fruit step-wise.
One or more ovules inside the ovary or ovaries are found where egg cells are present in the megagametophyte.
These ovulves become seeds after double fertilization.
The ovules are then fertilized in a process starting with pollination.
Pollination is the movement of the pollen from the stamens to the stigma of the flowers.
After pollination, the pollen leads to the growth of a tube through the stigma into the ovary to the ovule. Further, two sperms are transferred to the megagametophyte from the pollen.
Then, a zygote formation takes place with the unison of one of the sperms with the egg within the megagametophyte.
The second sperm then enters the central cell and forms the endosperm mother cell, thus, completing the double fertilization process.
Later, embryos of the seed are formed via zygote and the endosperm mother cell gives rise to the endosperm which is a nutritive tissue used by the embryo.
As the seeds develop into ovules, the ovary begins to ripen and the pericarp (ovary wall) may become fleshy (such as in berries or drupes) or a hard outer covering (such as in nuts).
The pericarp differentiates into 2 or 4 distinct layers known as the exocarp or epicarp, mesocarp and endocarp.
3 Modes of Fruit Development
Apocarpous fruit development from a single flower with one or more separate carpels; these are the simplest form of fruits.
Syncarpous fruit development from a single gynoecium with two or more carpels that are fused together.
Multiple fruits that rise from multiple flowers.
Different Kinds of Fruits
Simple Fruits
These can be either fleshy or dry and are formed as the result of ripening of a simple or compound ovary in a flower having only one pistil. Dry or simple fruits may be either dehiscent or indehiscent. Some of the fruits belonging to this category include strawberry, wheat, coconut, bean, radish seed, hazelnut, etc.
Simple fruits can be classified further into the following categories:
Drupes: These fruits contain a very hard seed inside themselves, thus, are also known as stone fruits. Some examples are plums and cherries.
Berries: These simple fruits have a juicy interior and have only one seed inside them in the center. Grapes and blueberries are some examples.
Pomes: The kind of simple fruits that grow on trees are known as poems. Papaya and apple are two examples of pomes.
Hesperidium and Pepo: These fruits are somewhat similar to the berries and have juicy centers but have a lot of seeds inside them scattered inside instead of one central seed. Citrus fruits and watermelons are some examples of such fruits.
Aggregate Fruit
These fruits result from single flowers with multiple carpels that are not joined together. It means that each pistil contains one carpel. Each of the pistils forms a fruitlet and collectively, the fruitlets are known as etaerio. Raspberry, blackberry and strawberry are examples of aggregate fruit.
Multiple Fruits
These are the fruits which are formed from a cluster of flowers known as inflorescence. These flowers mature into a single mass and examples include fig, mulberry, pineapple, breadfruit, etc. These types of fruits can also be further divided into two types:
Sorosis: This type of fruit develops from catkin, spikes and spadix type of inflorescences, such as jackfruits, mulberries and pineapples.
Syconus: This type of fruit develops from the hypanthium type of inflorescence.
Benefits and Uses of Fruits
Eating fruits is beneficial for the body as fruits are some of the major sources of essential vitamins and minerals for the body and they are also required for the proper functioning of the body. Citrus fruits are rich in vitamin C which helps prevent scurvy in humans. Fruits are an important part of a healthy diet as they provide nutrients without adding any calories. Research suggests eating fruits can lead to emotional well being and promote a good mood.
Various vitamins like vitamin A, vitamin B6, vitamin C, vitamin E, vitamin K, and folate found in different fruits help in regulating cholesterol levels thus promoting good heart health as well as keeping type-2 diabetes in check by providing the appropriate nutrients to the body. Potassium-rich fruits like bananas, apples, apricots, mangoes and melons help in regulating blood pressure and lower hypertension owing to the vasodilating properties of the mineral found in the fruits.
FAQs on Fruit
1. What are Berries? Give Some Examples of a True Berry
Berries are kind of fleshy fruits which are created from a single ovary and belong to the category of simple fruit. Here, the ovary can be a compound form, meaning with several carpels. Some of the berries include pepo (skin is hardened) and hesperidium (present with a rind and juicy interior). Banana, chilli pepper, gooseberry, grapes, guava, kiwi, tomato, eggplant and banana are all true berries.
2. What are Seedless Fruits?
Seedlessness is the result from the abortion of the embryonic plant which is produced by fertilization. It is the feature of some fruits such as bananas and pineapples. Parthenocarpy occurs where fruits set without fertilization and result in seedless fruit.
3. What is Seed Dissemination?
It is the method of dispersal of seeds that result in variations in fruit structures and formation of new offsprings too. IT is done by animals, water, wind or dehiscence. It follows the evolutionary mechanism for increasing dispersal distance away from the parent, via natural processes like wind.
4. What are Fruit Flies?
Fruit flies lay their eggs in the fruit flesh and are the species of flies. Fruit flies are responsible for causing huge damage to the fruit crops. One of the best examples is Queensland fruit fly.
5. What is called fruit in biology?
Fruit is a mature and ripened ovary. The ovary is the reproductive structure in the flower. The ovary encloses and protects the ovules until the ovules become fertilized and turn into seeds. The fruit eventually functions to spread the seeds or to attract dispersers.
6. What are the parts contained in the structure of a fruit?
Fruits are composed of two parts:
1. Pericarp
2. Seeds
Pericarp: It is the wall of the ovary that grows into the pericarp. Pericarp can be fleshy as in guava, mango etc. And can be dry as in walnut. Pericarp has three layers
Epicarp: It is the outermost layer.
Mesocarp: This is the middle layer which is the edible part.
Endocarp: Innermost layer where seeds are found.
7. What is pollination?
Pollination is the process by which pollen grains are transferred from another of flowers to the stigma. This is one of the processes by which offspring are produced.
8. How does pollination help in the development of fruit?
Pollination is the process by which pollen grains are transferred to the stigma of flowers. From their pollen germinates gives rise to pollen tubes, which enter the ovule inside the ovary for fertilization. After fertilization, the endosperm and embryo grow and the ovule develops into a seed and the ovary matures into a fruit.
