Fruits are an important part of plants and play a vital role in reproduction. They develop from the ovary of a flower after fertilisation and contain seeds. Fruits not only help in the protection and dispersal of seeds but also serve as a major source of nutrition for humans and animals.
A fruit is the mature ovary of a flowering plant that usually contains seeds. It forms after fertilisation and may also include other parts of the flower, such as the thalamus.
Fruit is basically a nutritious, fleshy, seed-bearing structure of the plant, which can be sour and sweet. In some cases, fruit forms from another part of the flower as well, instead of the ovaries. Fruit is normally the product of sexual reproduction, but it can also form without fertilisation, such fruit known as parthenocarpic fruits.
Classification of Fruit
Based on the number of flowers and ovaries involved, fruit is classified into:
1. Simple Fruit
Simple fruits develop from the ovary of a single flower. The monocarpellary or multicarpellary syncarpous ovary produces these fruits.
- Fleshy Fruits: Fleshy fruits have three layers of fruit wall: epicarp, mesocarp, and endocarp. These fruits are produced by a superior or inferior syncarpous gynoecium.
- Dry Fruits: The pericarp of simple dry fruits is typically dry and hard. Unlike fleshy fruits, the three layers of epicarp, mesocarp, and endocarp are present but are dry, thin, and fused together, making them indistinguishable from one another. In some dry fruits, the pericarp splits open at maturity and disperses the seeds. such fruits are called dehiscent fruits. In others, the pericarp remains closed at maturity and such fruits are called indehiscent fruits.
The pericarp is further divided into one or more seeded segments in some fruits. In schizocarpic fruits, the pericarp splits into one-seeded segments at maturity.
2. Aggregate Fruit
Aggregate fruits develop from a multicarpellary apocarpous ovary. Because each carpel is separated from the others in the apocarpous ovary, it develops into a fruitlet. These fruits produce a cluster of fruitlets known as etaerio.
- Follicle etaerio: An etaerio of follicles consists of a cluster of follicle fruits. Calotropis, Catharanthus, and Magnolia are some examples. In Calotropis, the ovaries remain separate while the stigmas are fused. In etaerio, there are only two follicles.
- Achene etaerio: Each fruit in this aggregate fruit is an achene. For example, Ranunculus, Strawberry, Rose, etc. In lotus, the spongy thalamus contains embedded achenes. The thalamus in strawberries is fleshy, with small achenes on its surface.
- Etaerio of berries: It is a grouping of tiny berries. Polyalthia, Custard-apple, etc. In Annona, the berries are closely arranged on the thalamus.
- Drupe etaerio: Many small drupes develop from different carpels in this type of fruit, like a raspberry. The drupe fruit is formed by the carpel of an apocarpous ovary.
3. Composite Fruit
Composite or multiple fruits develop from the entire inflorescence. In general, many ovaries and other floral parts combine to form the fruit in these fruits. There are two kinds of these:
- Sorosis: These fruits form from the spike, spadix, or catkin inflorescence. Examples include Jackfruit and Kevda (screwpine). Pistillate flowers develop around the peduncle of jackfruit (Kathal). The pericarp becomes spongy and fused during fruit formation.
- Syconus: Syconus develops from hypanthodium inflorescence, as seen in fig (Ficus).
Structure of Fruit
There are two main components of the Fruit i.e., the pericarp and the seed.
1. Pericarp
The fruit wall formed from the ovary wall is called the pericarp. Mostly, the edible part of the fruit is the pericarp. The pericarp is composed of 3 layers known as:
- Epicarp: The outermost skin of the fruit is known as the epicarp, also known as the exocarp.
- Mesocarp: The fleshy part of the fruit. It is present between the epicarp and endocarp.
- Endocarp: Endocarp is the innermost layer of the pericarp that surrounds the seed.
2. Seed
The seed develops from the fertilised ovule and is enclosed by the endocarp. A seed is formed from the ripened ovule of a flower after fertilisation. Seeds are characteristic reproductive structures of both angiosperms and gymnosperms.
Uses of Fruits
Fruits are the edible sour or sweet structure of the plant, which are the result of the sexual reproduction of the plant.
- Fruit is a source of food for humans and many animals.
- The fruit consists of essential nutrients and vitamins, which are necessary for a healthy life and help to fight disease.
- Fruits are the organic sweetener and colouring source in cooking.
- Many fruits are used for the extraction of oils, such as coconut, castor, and groundnut.
- Some fruits are used in Ayurvedic medicine.
- Fruits rich in vitamin C act as antioxidants and help protect the body from free radicals.