Difference Between Chasmogamous and Cleistogamous

Key Difference – Chasmogamous vs Cleistogamous
 

The key difference between Chasmogamous and Cleistogamous flowers is that Chasmogamous flowers expose reproductive parts out for the pollinators while Cleistogamous flowers hinder them from exposing the reproductive parts out and force self fertilization.

The flower is the reproductive structure of the Angiosperms. A Flower contains both male and female reproductive parts within it. Anthers produce pollen grains that carry male gametes while pistil bears female gametes. Pollens are transferred into the stigma of pistil by pollinators during the pollination. Once pollination occurs, syngamy or the fertilization of female and male gametes takes place. Some flowers show self fertilization while some flowers show cross fertilization. When cross fertilization is not feasible, flowers carry on self fertilization. Chasmogamous and Cleistogamous flowers are two main flower types.

CONTENTS

1. Overview and Key Difference
2. What is Chasmogamous
3. What is Cleistogamous
4. Similarities Between Chasmogamous and Cleistogamous
5. Side by Side Comparison – Chasmogamous vs Cleistogamous in Tabular Form
6. Summary

What is Chasmogamous?

Chasmogamy is a mechanism of pollination and the flowers that show chasmogamy are chasmogamous flowers. Chasmogamous flowers are prominent, and they open their floral parts including anthers and stigma of pistils for the pollination.

Chasmogamous flowers are bisexual and mostly show cross pollination. However, there is self pollinating chasmogamous flowers as well. Since cross pollination occurs, chasmogamous flowers require pollinators (abiotic or biotic pollinators). And also chasmogamous flowers produce seeds that are genetically distinct. Hence, these flowers increase the genetic diversity of the population, reduce the inbreeding depression, and retard the deleterious effects of recessive alleles.

What is Cleistogamous?

Cleistogamy is another type of pollinating mechanism in which pollination and fertilization occur in unopened flowers or flower buds. Those flowers are known as cleistogamous flowers. They don’t open their reproductive parts to the out. They remain closed, and they force self pollination and fertilization. Hence, cleistogamous flowers do not need pollinators or attractive floral parts or nectaries to reward pollinators.

These flowers are observed in the soil, and they are small and cannot be distinguished as flowers. Peanuts, peas, and pansy are examples for cleistogamous flowers.

What are the Similarities Between Chasmogamous and Cleistogamous?

• Chasmogamous and Cleistogamous flowers belong to angiosperms.
• Both Chasmogamous and Cleistogamous flowers show self fertilization.
• Flowers of Chasmogamous and Cleistogamous are bisexual.
• Pollination and fertilization occur in both Chasmogamous and Cleistogamous flowers.

What is the Difference Between Chasmogamous and Cleistogamous?

Chasmogamous vs Cleistogamous
Chasmogamous flowers are the flowers that expose their reproductive parts out for pollination.	Cleistogamous flowers are the flowers that do not open and hinder them from exposing the reproductive parts and force self fertilization.
Nature
Chasmogamous flowers are opened.	Cleistogamous flowers stay closed.
Fertilization
Chasmogamous flowers show both self and cross fertilization.	Cleistogamous flowers always show self fertilization.
Involvements of Biotic and Abiotic Pollinators
Chasmogamous flowers are pollinated by biotic or abiotic pollinators.	Pollinators are not involved with Cleistogamous flowers.
Exposing Anthers and Stigma
Chasmogamous flowers expose anthers and stigma.	Cleistogamous flowers never expose anthers and stigma.
Pollination and Fertilization
Pollination and fertilization of chasmogamous flowers occur after opening the flowers.	Pollination and fertilization of cleistogamous flowers occur while during the closed state.
Flowers
Chasmogamous flowers are prominent.	Cleistogamous flowers are not much distinguishable.
Attractive Floral Parts
Chasmogamous flowers posses attractive floral parts to attract pollinators.	Cleistogamous flowers do not possess attractive floral parts.
Coloured Petals
Chasmogamous flowers often posses coloured petals.	Cleistogamous flowers do not possess coloured petals.
Nectaries
Chasmogamous flowers have nectaries.	Cleistogamous flowers do not have nectaries.
Pollen Production
Chasmogamous flowers need to produce a large amount of pollen.	Cleistogamous flowers do not need to produce a large amount of pollen.
Requirement of Plant Resources to Produce Seeds
Chasmogamy needs comparatively higher plant resources for seed production.	Cleistogamy needs fewer amounts of plant resources to produce seeds.
Advantages
Chasmogamous flowers produce seeds that are genetically distinct hence, it increases genetic diversity, reduce inbreeding depression and deleterious effects of recessive alleles.	Cleistogamous flowers do not need pollinators for pollination. And also need fewer plant resources for seed production.
Disadvantages
Chasmogamous flowers need pollinators. Hence, they depend on pollinators.	Cleistogamous flowers produce seeds that are genetically similar. Hence, increases the inbreeding depression and deleterious effects of recessive alleles.

Summary – Chasmogamous vs Cleistogamous

Chasmogamous flowers perform pollination and fertilization after opening their floral parts. Both cross and self pollination occur in chasmogamous flowers, but cross pollination is most common and favoured. Cleistogamous flowers carry out pollination and fertilization before opening or inside the flower bud. However, they do not expose floral parts specially anthers and stigma. Hence, they always encourage the self pollination. This is the difference between chasmogamous and cleistogamous flowers.

Reference:

1.“Cleistogamy.” In Defense of Plants. Available here  
2.“Chasmogamy.” Wikipedia, Wikimedia Foundation, 17 Feb. 2018. Available here 

Image Courtesy:

1.’Chasmogamy’By As701914 – Own work (CC BY-SA 4.0) via Commons Wikimedia 
2.’Viola odorata (cleistogamous flower)’By Cptcv (CC BY-SA 2.5) via Commons Wikimedia