We have learned in previous articles about asexual reproduction in plants. We shall learn about sexual reproduction in plants.
What do you know about sexual reproduction in plants?
Plants reproduce sexually for the same reasons as any other organism- to maintain genetic diversity. Sexual reproduction in plants is limited to flowering plants. Flowering plants are those plants that produce flowers. Have you ever wondered why flowers are so colourful or smell so good?
Plants invest a lot of energy in producing flowers. The flowers are bright to attract insects and bees. These insects and bees transport the pollen from one flower to another, thus, helping with the process of sexual reproduction in plants.
Flowers have only one role- sexual reproduction in plants. We have studied about the parts of a flower previously. Can you recollect the parts of a flower?
Flowers are composed of sepals, petals, stamens and carpels. The sepals and petals protect the stamens and carpels. The stamens and carpels are the reproductive organs of the plant. The stamens are the male reproductive organs and the carpel is the female reproductive organ of a plant.
Plants are of two types- unisexual and bisexual.
Unisexual Plants– These plants have flowers that comprise only of stamens or carpels. Examples include papaya and watermelon. Therefore, these plants can only be fertilised by pollen from another plant.
Bisexual plants- Flowers of these plants contain both stamens and carpels. Thus, these plants can be fertilised by pollen from the same plant or another plant. Examples include Hibiscus and mustard.
Stamens produce pollen. Pollen is the sticky, yellow powder that sticks to our hands if we touch it. The powder corresponds to the male gamete of the plant. When bees and other insects come in contact with the pollen, the pollen sticks to their feet and are transported to other flowers. This process is called pollination. Bees play a critical role in pollination. We will discuss the role of bees in agriculture in another article.
The carpel is the female reproductive organ of the plant. The carpel comprises of the ovary, the style and the stigma. The ovary is the bottom, swollen part of the carpel. The style is an elongated tube that functions to transport the pollen and the stigma is the sticky top part of the carpel. Pollen is deposited on the stigma and it travels through the style to reach the ovary. Here, it fuses with the female gamete to produce seeds. Once a flower is pollinated, the rest of the parts of the flower shrivel and fall off.
There are two terms one usually comes across about pollination:-
Self-pollination- Pollen from the same plant fertilise the ovule.
Cross-pollination– Pollen from another plant fertilises the ovule.
To summarise, sexual reproduction in plants is vital for maintaining genetic diversity and forms the basis of most agricultural innovation. Flowers are the reproductive organs of the plants and these flowers can either be fertilised by pollen from the same plant or another plant.
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