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Cleistogamy

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What is Cleistogamy?

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Cleistogamy is a phenomenon that occurs in different types of plants. Here, fertilisation generally occurs in closed plants that do not open. They follow self-pollination and undergo fertilisation. Pollination is the process of transferring pollen grains from a flower's male anther to its female stigma. Every living organism, including plants, strives to produce offspring for the next generation. Plants can produce offspring in a variety of ways, including by producing seeds. The transfer of pollen grains from the anther to the stigma of the same flower is known as self-pollination.


We will discuss every detail about cleistogamous flowers, cleistogamy pollination, and cleistogamous flowers’ example in this article along with some FAQs. This topic is full of facts and should be revised frequently. Studying this topic will also help students understand the whole chapter accurately.


What is Cleistogamy Pollination?

Cleistogamy pollination is a type of pollination in a specific type of flower that does not open at all, not even for pollination or fertilisation. Such flowers are known as cleistogamous flowers. The literal meaning of cleistogamy is closed marriage. The flowers that follow this phenomenon undergo self-pollination and self-fertilisation. This phenomenon is also known as autogamy. Autogamy is a type of self-pollination, where the flowers self-pollinate themselves.


Types of Cleistogamy

Cleistogamy is further divided into 4 types that are described below as follows:

  • Parenthesis Cleistogamy: In this type of cleistogamy, pollination occurs when the flower is in its bud stage and opens during the later stage of life. An example of it is Cuscuta.

  • Pseudo Cleistogamy: Here, both kinds of flowers are present, i.e., open and closed flowers, but only the closed flowers perform cleistogamy.

  • Complete Cleistogamy: Here, only closed flowers are present that perform self-pollination.

  • True Cleistogamy: The open flowers and closed flowers are morphologically different. The open flowers are large compared to the closed flowers. Therefore, only the closed flowers are modified to perform autogamy.


What are Cleistogamous Flowers?

It is a type of flower that performs cleistogamy. The cleistogamous flowers do not open and follow autogamy or self-pollination. These flowers produce a specific set of seeds as they do not have to depend on any external factor for pollination. In cleistogamous flowers, the male and female reproductive parts are smaller. Cleistogamous flower examples are peas, peanuts, etc.


Advantages of Cleistogamy

The advantages of cleistogamy are as follows:

  • As the flowers following cleistogamy are self-pollinated, they do not depend on any other external factor for fertilization.

  • It helps the plants produce a specified number of seeds even if the environmental conditions are adverse.

  • The flowers can avoid the synthesis of large amounts of pollen grains and nectar as there is no chance of loss in cleistogamy.

  • Through this method, the population of plants is maintained even in adverse environmental conditions.


Disadvantages of Cleistogamy

There are a few disadvantages to cleistogamy such as plants following cleistogamy have reduced genetic variation, which can lead to inbreeding depression. Inbreeding depression may result from continued self-pollination. This self-pollination does not aid in the development of new varieties and species. Cleistogamous flowers are almost always autogamous. As a result, there is no chance of cross-pollination.


Conclusion

Cleistogamy is a way through which flowers pollinate, but the unique part about cleistogamy pollination is that the flowers self-pollinate themselves. Here, the flowers remain close throughout their lives and undergo self-pollination. There are various advantages and disadvantages of cleistogamy, like how it reduces the dependency of the plant on external factors for pollination but loses the genetic variation that causes inbreeding depression. Cleistogamous flowers are those that exhibit cleistogamy. It is well known among members of the grass family, including peas, peanuts, and pansy.


This article mentions all the necessary concepts related to cleistogamy. This is an important topic for Class 12 under the chapter ‘Sexual Reproduction of Plants’ and this article would help students gain an understanding concept of the given topic.

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FAQs on Cleistogamy

1. Do all flowers show autogamy? What are the necessary characteristics for autogamy?

No, not all flowers show an autogamy mode of pollination. Only a few flowers show an autogamy mode of pollination, like cleistogamous flowers. There are a few characteristics that are necessary to show autogamy. Some of them are:

  • There should be a synchronisation between the release of pollen grains and the receptivity of the stigma of the plant so that pollination can occur.

  • The male reproductive part (anther) and the female reproductive part (stigma) should be close to each other so that the pollen can transfer easily.

  • The phenomenon of autogamy is not possible for flowers where the male and female reproductive parts are exposed.

2. What is the difference between cleistogamy and chasmogamy?

The difference between cleistogamy and chasmogamy is as follows:

Cleistogamy

Chasmogamy

In cleistogamy, pollination occurs in closed flowers.

In Chasmogamy, pollination occurs in open flowers.

The flowers are known as cleistogamous flowers.

The flowers are known as chasmogamous flowers.

Here, the plants only undergo self-pollination.

Here, the plants may undergo cross-pollination or self-pollination.

This type of pollination does not depend on pollinators or any other external factors.

This type of pollination depends on pollinators and external factors.

Example- Commelina

Example- Hibiscus

3. What is meant by herkogamy?

Herkogamy is a key floral trait thought to promote outcrossing or the avoidance of interference between male and female sexual functions. Herkogamy may serve primarily to reduce sexual interference in self-incompatible species, whereas, in self-compatible plants, it is usually regarded as an adaptive trait that reduces the likelihood of self-pollination and increases the possibility of outcrossing. The placement of male (staminate) and female (pistillate) flowers in different positions within the same plant in bisexual flowers; for example, a heterostylous species is also a herkogamous species. It favours cross-pollination. 


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