Chasmogamy: A special Reproductive Mechanism in Flowers

Chasmogamy is a reproductive mechanism in plants that helps in the cross-pollination of flowers. The flowers which show chasmogamy are known as chasmogamous flowers. The word chasmogamous has been taken from the Greek dictionary, which means ‘open marriage’. These flowers open at maturation, before fertilisation for easy pollination.

Examples: Viola, Monochoria, Lamium, rose, cotton, eggplant, etc.

Features of a Chasmogamous Flower

  • The flowers are showy and have open petals.
  • The reproductive parts are large and exposed to aid cross-pollination.
  • The petals are brightly coloured.
  • There are nectaries in the flowers to attract pollinators.
  • The flowers are usually dichogamous, the male and female reproductive parts mature at different times to promote cross-pollination.

Note: Chasmogamous flowers can sometimes show self-pollination.

Advantages of Chasmogamy

  • Cross-pollination in chasmogamous flowers promotes sexual recombination and genetic diversity in the seeds produced.
  • The genetically distinct seeds help in overcoming inbreeding depression and avoiding deleterious alleles.
  • The seeds have increased vigour and fitness.

Disadvantages of Chasmogamy

  • The development of attractive flowers requires a lot of energy and resources.
  • The production of seeds is totally dependent on pollinators.
  • Resources like light, water, and nutrients are required at high rates.

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Frequently Asked Questions


What are chasmogamous and cleistogamous flowers?

Chasmogamous flowers are open and showy and undergo cross-pollination, whereas cleistogamous flowers are closed and undergo self-pollination.


Do chasmogamous flowers require pollinating agents?

Yes, chasmogamous flowers require pollinating agents for cross-pollination.


Can chasmogamous flowers undergo autogamy?

When both the male and reproductive parts of the flower mature at the same time, there are high chances of the chasmogamous flowers showing autogamy.


Do chasmogamous flowers always show geitonogamy?

Chasmogamous flowers have the tendency to show autogamy, geitonogamy and xenogamy.


Are sunflowers chasmogamous?

Yes, sunflowers are chasmogamous.


Why do some plants have both chasmogamous and cleistogamous flowers?

The presence of both chasmogamous and cleistogamous flowers ensures pollination and fertilisation, whether the flower is open or not.


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