As we all know, trees are usually named and recognized by their fruit such as apple tree, mango tree, coconut tree and so on. A fruit is an important and characteristic part of the plants, especially the angiosperms. It is the fleshy, seed-bearing, (mostly) edible structure of the plants. Some fruits are fleshy, sweet, and juicy, while others are sour. Few fruits have seeds and others are seedless.
What is a fruit?
We know what a fruit looks like, but how do you actually define a fruit? Typically, seeds are required for most plants to propagate or create new individuals. These seeds are enclosed in a structure called the fruit. But these structures are only seen in the angiosperms or the “flowering plants.” In other words, fruits help in the reproduction of these plants by disseminating seeds. Another important aspect to remember is that all fruits are formed from flowers, but not all flowers produce fruits.
“Seedless fruits” like oranges, watermelons are like a contradiction, this is because fruits – scientifically speaking, are supposed to be the mature ovaries that contain seeds. There are two ways in which a seedless fruit can occur, namely, Parthenocarpy and Stenospermocarpy. Plants in which fruits develop without fertilization are called parthenocarpic fruits (e.g., banana). Stenospermocarpy fruits, on the other hand, form when pollination occurs, but the embryo is aborted post-fertilization. (e.g., seedless grapes).
Parts of a Fruit
As stated above, a flower is a reproductive unit and the fruits are the outcome of reproduction. Botanically, a fruit is defined as the matured, ripened ovary shaped after syngamy. During reproduction in angiosperms, the sperms from the pollen grains fuse with the ovules enclosed in the ovary. After fertilization, the ovary transforms into fruit and ovules mature into seeds simultaneously.
In the majority of angiosperms, the flower disintegrates and sheds off by the time fruits are formed. In fruits like apple, strawberry, the thalamus also forms the fleshy part. These type of fruits are called false fruits and the fruits that develop only from the ovary are called true fruits.
Simple fruits consist of an edible section called the pericarp, which houses the seeds. The pericarp is the wall of the ovary that develops as the wall of the fruits. The pericarp of the fruits might be fleshy as in guava, mango, etc. or might be dry as in mustards, walnut, etc. The pericarp is further differentiated into three layers, namely:
- Internal layer (the Endocarp)
- Middle layer (the Mesocarp)
- External layer (the Exocarp)
The exocarp (also called epicarp) forms the peel, mesocarp is the fleshy, edible portion of the fruits and endocarp is the inner rough portion where the seed is accommodated. Generally, fruits that developed from a monocarpellary superior ovary are single-seeded in nature.
Types of Fruits
Based on the number of ovaries and the number of flowers involved in the fruit formation, fruits are classified into three major groups namely:
These fruits, develop from a single matured ovary in a single flower. Apple, banana, cherry pear, plum, tomato are few examples of simple fruits.
These fruits, develop from a number of matured ovaries formed in a single flower. Individual ovaries are called “fruitlets.” Blackberry, raspberry, strawberry are few examples of aggregate fruits.
These fruits, develop from the matured ovaries of several to many flowers more or less united into a mass. Fig, mulberry, and pineapple, are few examples of multiple fruits.
Uses of Fruits
Fruits are rich in minerals and vitamins which are essential for a healthy human body. For instance, we know that oranges are rich in vitamin C. Vitamin C is vital to neutralize any free radicals in our body. Also, acids in citrus fruits are very effective in skin whitening and exfoliation. Besides consumption, these citrus acids can help to get rid of mineral deposits and grease on cooking utensils.
Fibre-rich fruits like raspberries are very good for digestion. The protein in papaya, called papain, can help the breakdown of proteins, and therefore aid digestion. It is also reduces acidity levels and eases indigestion.
Palm dates have low glycemic index and hence, they are very useful in blood sugar regulation. Furthermore, it is high in dietary fiber and is very helpful for digestion.
Grapes have a chemical called Reservatrol that functions similar to aspirin, giving it the properties of an analgesic (painkillers).
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