Pollination: Definition, Types, Agents & Process

Here in this article, we are going to discuss “Pollination: Definition, Types, Agents & Process”. This topic is very important with respect to science students. we will try to teach you in a very simple way by including all important points with examples.

Pollination is the process of transfer of pollen grains for fertilization. In the pollination pollen grain transferred from an anther to the stigma of the same flower or of a different flower. Pollination is the main characteristics feature of gymnosperms and angiosperms.

Types of Pollination

There are two types of pollination found in nature.
1. Self-pollination and 2. cross-pollination

1. Self-Pollination: Types, Adaptations, Merits & Demerits

As we already know that in the case of self-pollination only a plant is involved for both gender. Self-pollination is further divided into two types

I) Types of Self Pollination

Self-pollination and cross-pollination having it’s on importance. Now see the merits and demerits of self-pollination.

II) Merits of self-pollination

• In the self-pollination, pollen grains are not wasted in the case of self-pollination,
• The purity of generation is maintained in the alternation of generation.

III) Demerits of self-pollination

• New and healthy and varieties are not formed after self-pollination .
• Self-pollination results in weaker progeny producing weaker seeds and plants.

IV) Adaptations and requirements for self-pollination

The major requirements which are very important for self-pollination. Here is a list of measure requirements or adaptations.

Maturity time of anther and stigma of bisexual flower should be the same. This process is called homogamy. Growth, bending for the folding process of anther and stigma should be closed to each other in respect of the maturity time.

Hermaphrodite or bisexual flower is very important for self-pollination. In the simple word, both male (androecium) and female sex organs (gynoecium) should be in a flower.

In the case of some plants, they never open to ensuring complete self-pollination. Such type of plants never secretes nectar. Oxalis, viola are examples of cleistogamy.

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2.Cross-Pollination: Types, Adaptations, Merits & Demerits

Transfer of pollen grains from the flower of one plant to the stigma of the flower of another plant is called cross-pollination.

I) Requirements or adaptations for cross-pollination

Cross-pollination is nature favourite. This is very important to survive in a changing the environment. These Some requirements for cross-pollination

This is the condition of the plant, capable of producing only male or female gametes. The plant never has both sex organs. In other word stamen and carpels are found in different flowers never on the same flower.

There are two types of plants on the basis of unisexuality
A) Monoecious plants- male and female flowers are born on the same plant

B)Dioecious plant- male and female flowers are born on the different plants

The time of maturity of flowers is different from each other to stop or prevent self-pollination.

There are two conditions
Protandry- when stamens Mature earlier than the stigma
Protogy- when stigma mature earlier than stamens

In the case of some plants, the length of Style and stamens is different for cross-pollination.

A) Pineyed- flower possesses a long style but short stamens
B) Thrum eyed- flower poses long stamens and short style

stigma and anthers mature at the same time in some bisexual flowers. But to avoid self-pollination there is some sort of barriers. The distance between male and female sex organs Structure of corolla has a Peculiar form to avoid self-pollination. In the case of orchid and calotropis pollen Grain are held together to form pollinia which can only be carried away by insects.

Pollen grains are unable to germinate on the stigma of the same flower. The condition is called self sterility.

II) Agents for Cross-Pollination

Cross-pollination is the transfer of pollen grain from the flower of one plant to the of another plant. This process needs agents to get complete. These agents transfer the Pollen Grain from one plant to another plant. Here we are going to discuss the agents involved in the cross-pollination.

Abiotic agents

Abiotic agents are non-living things which are helpful to transfer the Pollen Grain from one plant to another plant. Examples- wind, water etc

The transfer of pollen grain with the help of water is called hydrophily and the transfer of pollen grain from one plant to another plant by wind is called anemophily. Example: sugarcane, Mage wheat, bamboo, papaya, glasses coconut, Mulberry etc

Examples- Najas, Ceratophyllum, Zostera, Vallisneria etc

Biotic Agents

Biotic agents are the living organisms which are helpful to transfer of pollen grain from one plant to another plant four cross-pollination purpose.

Examples- Insects, birds, Bats, Snails, ants

Transfer of pollen grain from one plant to another plant with the help of an insect is called entomophily Ex- yucca, orchid

Flowers are pollinated by the help of birds is called orthinophily. Sunbirds, hummingbird, crow, bulbul, parrot are the major class of birds which are very helpful to transfer the Pollen Grain from one plant to another plant. Examples– Bignoniya, Agave, Bombax etc

the transfer of pollen grain from one plant to another plant with the help of bats is called Chiropterophily. Examples: Kigelia, adansonia, bauhinia megalandra etc

when the transfer of pollen grain from one plant to another plant with the help of slugs and snails is called malacophily. Examples- Chrysanthemum

Transfer of pollen grain from one plant to another plant with the help of ants is called Myrmecophily. Examples- Anemone nemarosa.

III) Merits of Cross-Pollination

• Seeds are more and viable naturally
• Healthier progeny formed
• Better adaptability of progeny
• New variety can be formed by cross-pollination

IV) Demerits of Cross-Pollination

• Agents required to complete cross-pollination
• Pollen grains are wasted in a large number

Read more

Pollination: Definition, Types, Agents & Process

Reproduction in Flowering plants: Types, Process and Examples

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Conclusion

After the pollination fertilization takes place to develop the embryo. Then embryo developed into a whole plant after getting food and nutrition. Here we have only discussed Pollination: Definition, Types, Agents & Process. Now in the next article, we will learn about Fertilization.

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