[Biology Class Notes] on Types of Pollination Pdf

Before jumping into pollination types, we should first learn about the concept of pollination. 

The basic goal for every living being on our planet is to have offspring. 

Plants don’t reproduce like us but that doesn’t mean they don’t. Their reproduction is termed asexual reproduction. Plants reproduce by generating seeds. In producing a new plant, the genetic information needed is found in seeds. 

The tool that a plant uses to create a seed is a flower. Seeds can only be generated by one method that is when the same species of flowers transfer the pollen to each other. The whole act of transferring pollen grains from male anther to female anther is termed pollination. 

All plants need to propagate for the growth and survival of their species. Plants reproduce by pollination. Flowers help plants to propagate. A flower is the most beautiful part of the plant and the one responsible for the process of pollination. Pollination is the transfer of pollen grains produced by the flower from its anther to the stigma of the same or different flower. This process takes the help of natural agents like birds, insects, and biological agents like the water and the wind. These are known as pollinating agents. They are also called “pollinators”. 

Pollination is the result of the unintentional activities of an animal on a flower. When the pollinator eats and Collects the protein along with other nutrients from the pollen or when it’s sipping the nectar from the flower, that time pollen grains attach themselves to the body of the pollinator. When that animal goes to the other flower, pollen often falls on the stigma of that flower and results in the successful reproduction of the flower. 

After this, pollen from the first flower’s anther deposits on the stigma of flower number two. Pollen most likely germinates on the stigma of the flower which states that it formed a “pollen tube” on the surface of the stigma that is sticky and then they shift to grow in the ovule of the plant. 

The Three Conclusions of this Growth: 

1. The flower is fertilized successfully and the seeds, fruits have started growing. 

2. There could be a possibility that the plant is fertilized partially, which means the seeds and the fruits may not grow fully. 

3. This results in the plant failing to pollinate and won’t grow at all. 

Pollination of the pollen grains can occur in the same flower or in two different flowers. Based upon the location of transfer of the pollen, pollination is of the following two types.

• Self-Pollination 

• Cross-Pollination

We will now study these two methods of pollination and what is the difference between self-pollination and cross-pollination. 

What is Self-pollination?

Self-pollination happens on a single flower. It is the primary method of pollination. It involves the transfer of pollen grains from the anther to the stigma part of the same flower. The process is straightforward and quick, and easy to understand, as well.

In this process, the pollen grains from the anther or the flower’s male reproductive structure get transferred to the stigma or the female reproductive structure of the same flower or of another flower on the same plant. The pollen grains are carried by the wind, water, or animals.

Plants like orchids, oats, legumes, peas, sunflowers, peanuts, peaches, potatoes, and wheat follow self-pollination. In the case of self-pollination, the same plant’s genetic material is used to form gametes, and finally, the zygote. Hence, self-pollination leads to the production of plants that do not have genetic diversity. 

Self-pollination occurs in flowers when both the reproductive parts, the stamen and the carpel, mature at the same time. This method does not require any pollinating agents or any nectar and pollen to attract insects or birds.

Types of Self-Pollination: 

Self-pollination consists of two types: autogamy and geitonogamy. 

When the transfer of pollen is done to the stigma of the same flower, it is known as autogamy. 

When the transfer of pollen happens from another of flower one to the stigma of flower two on the same flower with one gymnosperm, it is known as geitonogamy. 

What is Cross-Pollination?

Cross-pollination is the second and more diverse form of pollination. It occurs when there is a transfer of pollen grains from the anther of one flower to the stigma of another flower. The destination flower is a different flower of the same species. This method of pollination leads to an increase in genetic diversity. It is because the genetic information from different flowers gets shared and crossed. It results in the creation of unique offspring. In this case, the reproductive process takes place in different plants.

Cross-pollination is also known as heterogamy. It is a type of pollination where pollen grains which are sperm-laden get transferred from the flowers of plant one to the second flowers which are egg-bearing. 

It is found in both flowering plants and cone-bearing plants. 

Cross-pollination can be carried out by wind as well as bees and other birds or animals. Insects cross-pollinate many fruit-bearing plants like apples, strawberries, raspberries, grapes, plums, and flowers like tulips and daffodils. Wind pollination can be observed in different grasses, maple trees, and dandelions.

Differentiate between Cross-pollination and Self-pollination

Have you ever wondered how self-pollination is different from cross-pollination? Self-pollination and cross-pollination are common pollination methods, but there is a vital difference between self-pollination and cross-pollination. The diagram below shows this.

Self-pollination and Cross-Pollination Diagram 

(Image will be Updated Soon)

You can see that the pollen from the anther of the flower gets deposited onto the stigma of the same flower in the first flower.

In the second flower, you can see how the pollen from another flower gets deposited on its stigma.

This picture clearly shows the self-pollination and cross-pollination differences.

Now we will differentiate between self-pollination and cross-pollination with the help of the table below.

Pollination Fun Facts

Butterflies prefer flowers with flat petals where they can easily land.

Hummingbirds like long and tube-shaped flowers in red, pink, or fuchsia colors.

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