What is cleistogamy definition process advantages and examples
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.
FAQs on Cleistogamy in Flowering Plants
1. What is cleistogamy in biology?
Cleistogamy is a type of self-pollination in which flowers remain closed and fertilization occurs within the same flower. In cleistogamous flowers, the anthers release pollen directly onto the stigma without opening, ensuring self-fertilization.
- The flowers do not open at all.
- Pollination and fertilization occur internally.
- It guarantees seed formation even in the absence of pollinators.
2. How does cleistogamy occur?
Cleistogamy occurs when pollen grains from the anther fertilize the ovules of the same closed flower. The process involves:
- Anther dehiscence inside the unopened flower.
- Pollen transfer directly to the stigma of the same flower.
- Growth of the pollen tube toward the ovule.
- Fertilization and seed development.
3. What is the difference between cleistogamy and chasmogamy?
The main difference between cleistogamy and chasmogamy is that cleistogamous flowers remain closed while chasmogamous flowers open for pollination. Key differences include:
- Cleistogamy: Flowers remain closed; always self-pollinated; no pollinators required.
- Chasmogamy: Flowers open; may undergo self- or cross-pollination; often depend on pollinators like insects or wind.
- Cleistogamy ensures reproductive success, while chasmogamy promotes genetic variation.
4. What are examples of cleistogamous plants?
Common examples of cleistogamous plants include Viola, Oxalis, and Commelina. In these plants:
- Small, inconspicuous closed flowers perform cleistogamy.
- Some species also produce open chasmogamous flowers during favorable conditions.
- Seed set is guaranteed even without pollinators.
5. What are the advantages of cleistogamy?
The main advantage of cleistogamy is assured seed production through self-fertilization. Additional advantages include:
- No dependence on external pollinating agents.
- Lower energy expenditure on attracting pollinators.
- Maintenance of stable parental traits.
- Successful reproduction in adverse environmental conditions.
6. What are the disadvantages of cleistogamy?
The major disadvantage of cleistogamy is reduced genetic variation due to continuous self-pollination. Other drawbacks include:
- Increased risk of inbreeding depression.
- Limited adaptability to changing environments.
- Accumulation of harmful mutations over generations.
7. Is cleistogamy a type of self-pollination?
Yes, cleistogamy is a specialized form of self-pollination that occurs in closed flowers. Unlike other forms of autogamy, cleistogamy ensures that:
- The flower never opens.
- Cross-pollination is completely prevented.
- Fertilization occurs within the same floral structure.
8. Why do some plants produce both cleistogamous and chasmogamous flowers?
Some plants produce both cleistogamous and chasmogamous flowers to balance reproductive assurance and genetic diversity. This dual strategy allows:
- Cleistogamous flowers to ensure seed set under unfavorable conditions.
- Chasmogamous flowers to promote cross-pollination and variation when pollinators are available.
- Greater survival and adaptability across environments.
9. How is cleistogamy an adaptation in plants?
Cleistogamy is an adaptation that ensures reproductive success in environments where pollinators are scarce or conditions are harsh. It helps plants by:
- Guaranteeing fertilization without external agents.
- Reducing dependence on climate or seasonal pollinator activity.
- Conserving resources otherwise used for large, showy flowers.
10. Does cleistogamy prevent cross-pollination completely?
Yes, cleistogamy completely prevents cross-pollination because the flower never opens to external pollen. Since the stigma receives pollen only from its own anther:
- No foreign pollen can enter.
- Genetic exchange between different plants does not occur.
- Offspring are genetically very similar to the parent plant.
