What is the Difference Between Chasmogamous and Cleistogamous

The main difference between chasmogamous and cleistogamous is that chasmogamous flowers are open and showy, exposing their reproductive structures to the outside, whereas cleistogamous flowers remain closed and hidden so that anthers and stigmas are never exposed. 

Chasmogamous and cleistogamous are two terms that explain the position of reproductive structures in flowers. Chasmogamous flowers encourage cross-pollination while cleistogamous flowers restrict cross-pollination and undergo self-pollination.

Key Areas Covered

1. What is Chasmogamous
     – Definition, Features, Importance
2. What is Cleistogamous
     – Definition, features, Importance
3. What are the Similarities Between Chasmogamous and Cleistogamous
     – Outline of Common Features
4. What is the Difference Between Chasmogamous and Cleistogamous
     – Comparison of Key Differences

Key Terms

Chasmogamous, Cleistogamous, Cross-Pollination, Petals, Reproductive Structures, Self-Pollination

What is Chasmogamous

Chasmogamous is the condition of having large and showy flowers with opened petals to expose the reproductive structures of the flower to the outside. In Greek, chasmogamous means “open marriage”. That means; chasmogamous flowers undergo cross-pollination. Therefore, these flowers have prominent petals or petaloid, which are colourful and large in order to attract pollinators. However, some chasmogamous flowers undergo cross-pollination by other abiotic pollination agents such as wind.

Figure 1: Purple Pansy

Generally, undergoing cross-pollination is beneficial as it leads to sexual recombination through which new combinations of genetic factors arise, fitting more to the environment. That means; the cross-pollination facilitates evolution.

What is Cleistogamous

Cleistogamous is the condition of having small, hidden flowers with closed petals at maturity. Therefore, the reproductive structures of these flowers are not exposed to the outside. In Greek, cleistogamous means “closed marriage”. Moreover, cleistogamous flowers undergo self-pollination. Also, they do not require external pollinating agents to carry out pollination. Here, the pollen grains produced by the stamen deposit on the stigma of the same flower.

Figure 2: Self-Pollination

Self-pollination is important for preserving some of the beneficial genotypes of the species through successive generations. However, it does not lead to evolution, which occurs through the emergence of new genotypes.

Similarities Between Chasmogamous and Cleistogamous

• Chasmogamous and cleistogamous are two conditions of flowers, the reproductive organ of the angiosperms.
• They have significant adaptations to encourage a particular type of pollination.
• However, both types of flowers have reproductive structures including stamen and pistil.

Difference Between Chasmogamous and Cleistogamous

Definition

Chasmogamous refers to the production of flowers that open, so as to expose the reproductive organs and allow cross-pollination, while cleistogamous refers to the condition of having small, unopened, self-pollinating flowers, usually in addition to showier flowers. Thus, this is the main difference between chasmogamous and cleistogamous.

Size of Flowers

Generally, chasmogamous flowers are large and more prominent while cleistogamous flowers are very small and indistinguishable.

Colour of Flowers

Also, another difference between chasmogamous and cleistogamous is that chasmogamous flowers have bright colours while cleistogamous flowers are less colourful.

Petals

Moreover, chasmogamous flowers have petals or petaloid to attract pollinators while cleistogamous flowers generally do not have petals.

Status

Importantly, chasmogamous flowers are open and showy, exposing their reproductive structures to the outside while cleistogamous flowers remain closed and hidden so that anthers and stigmas are never exposed.

External Pollinating Agents

Pollinating agents are another difference between chasmogamous and cleistogamous flowers. Chasmogamous flowers require external pollinating agents while cleistogamous flowers do not require external pollinating agents.

Type of Pollination

Furthermore, chasmogamous flowers mainly undergo cross-pollination while cleistogamous flowers mainly undergo self-pollination.

Examples

Pansy is an example of chasmogamous flowers while Subularia is an example of cleistogamous flowers.

Conclusion

Chasmogamous flowers are open flowers with exposed reproductive structures. Moreover, they have large and colourful petals to attract pollinators. Therefore, these flowers undergo cross-pollination. On the other hand, cleistogamous flowers are closed flowers with no exposed reproductive structures. Also, some of these flowers do not contain petals at all. However, these flowers prevent cross-pollination and encourage self-pollination. Therefore, the main difference between chasmogamous and cleistogamous is the structure of the flower and the type of pollination they undergo.

References:

1. Lambers, Hans. “Plant Reproductive System.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 21 Nov. 2018, Available Here.

Image Courtesy:

1. “Purple Pansy” By The original uploader was Schoinard at English Wikipedia. – Transferred from en.wikipedia to Commons. (Public Domain) via Commons Wikimedia   
2. “Self-pollination(1)” By Jankula00 – Own work (CC BY-SA 4.0) via Commons Wikimedia