At the end of the article, you will be able to describe – What is pollination- Definition, Process, Why it is important, types, agents of the pollination. Let’s start discussing one by one.
What is Pollination – Definition
Pollination is the transfer of pollen to a stigma (ovule) of flower, or plant. This results in fertilization. If you look at flowers they are always so pretty. There are two kinds of flowers. A flower which has both the male and female parts is called a Perfect flower. And the flower which has either male or female parts is called an Imperfect flower.
- Male Part: Anther and Filament are the male parts of a flower. Jointly, they are called Stamen.
- Female Part: Stigma, Style, Ovary, and Ovules are the female parts. And together, they are called the Pistil.
Must Read: Parts of Flower.
The Filament is a long tube that supports the Anther. The pollen grains produced by the Anther. Pollen is a fine powder it’s usually yellow in color. The grain represents a group. In other words, it is a set yellow powder substance called as pollen grains.
The Petals and the Sepals – A Petal is a protective layer for the style and stigma. It is also the most attractive part of the flower. Petals attract insects. The Sepals are the green leaf-like structures parts at the base of the flower which protects the developing bud of a plant.
Pollen grains help these flowers reproduce and give birth to baby plants. Many a time, insects sit on these flowers and carry these pollen grains to the stigma. Stigma is the sticky surface at the top of the pistil which helps in trapping and holding the pollen grains.
Sometimes, these pollen grains are also carried by the wind. The Pollen grains land on the stigma (female part). There they germinate and form pollen tubes that grow through the spaces inside the style. The style is a tube-like structure that holds up the stigma.
At the end of the pollen tube, there is the pollen tip which reaches the Ovary and fertilizes the egg. When these pollen grains fuse with the ovules of the flower, a seed is formed which later grows up to become a handsome plant.
After the pollination, the ovary swells up turns into the fruit and the ovule inside the ovary turns into the seed. The new plant develops from the embryo inside the seed. this embryo develops from a single cell zygote. The zygote got develops into the embryo. then embryo develops into the baby plant. so all start from a single cell zygote.
How is zygote formed?
Starting from the beginning, a bead came and dropped the pollen grain in stigma. Hence, pollination is done. The pollen grains need to be transferred to the stigma.
The pollen grains consist of one kind of (male) gamete cell and another kind of gamete resides inside the ovules (female). If the pollen lands on the stigma of the right type of flower then the stigma secretes some nutrients. These nutrients are absorbed by the pollen grains and start growing a thin tube grows out of the pollen grain. The tube keeps growing carrying the male gamete and it grows until it reaches the ovary. The tube reaches the ovary and then it enters inside of ovule and releases the male gamete. Inside, the male gamete and the female gamete fuse together to form a zygote.
So, when two different types of gamete cells fuse the zygote is formed. This zygote grows into an embryo.
- As the pollen grain comes from the male part of the flower it consists of the male gamete.
- The ovule consists of the female gamete.
- This process of fusion of male gamete and the female gamete to form a zygote is called the fertilization.
Types of Pollination
We know that the insects help in the pollination. They help in that is transferring pollen grains from the anther (part of the male organ – stamen) to the stigma (part of the female organ – pistol).
- If the pollen grains are transferred to the stigma of the same flower it is called self-pollination.
- When the pollens are transferred from the anther of one flower to the stigma of another flower of the same kind it is called cross-pollination.
Why Pollination is Important?
Pollination is the process which is required to produce fruits and seeds that are essential for the next generation. Foods that we eat every day cannot be made without agents that help pollinate flowers. This could be wind, water, insects, that might monkeys or even bird pollination.
Broccoli, the vegetable that we all love is nothing but a flower. After pollination, the ovary of the flower becomes a fruit.
The hibiscus plant – The same flower has both the male and the female gametes. Hence the flower is called the bisexual flower or the complete flower.
Pumpkin – While in other plants, for example, pumpkin, corn, papaya etc. The flower has either the male gamete or the female gamete. Hence the flower is called the unisexual flower or the incomplete flower.
Agents of Pollination
The pollination happens due to the external agents. The External agent may be such as bee insects, wind, water also helps in the pollination. Hence, all of these are called the agents of pollination. The insects visit the flowers for nectar and transfer the Pollens to the stigma. Generally, the insect-pollinated flowers are brightly colored and have a sweet smell. They are also rich in nectar.
Some plants have small flowers and the petals are not brightly colored. They do not produce nectar. The Pollen grains of these plants are very light in weight and hence easily blown away by the wind. So, the wind is the agent of pollination. For example in the case of weed, maize, rice etc.
- In certain aquatic plants like the seagrass, the pollination is carried out by the water. As the water current slowly carries the pollen grains to the other flowers.
- You know even few small birds like the Sunbird or the hummingbirds which have smaller beaks pollinate the flowers. Few bats and rodents also pollinate the flowers.
This is all about the basics of –What is pollination- Definition, Process, Why it is important, types, agents of the pollination.