Question

List three strategies that a bisexual chasmogamous flower can evolve to prevent self pollination (autogamy).

Answer 1

Bisexual chasmogamous flowers

Chasmogamous bisexual flowers are the type of flowers with both male and female reproductive organs ,which are open and expose the anther and stigma to the outer environment. To retain genetic diversity these flowers have evolved ways to prevent self pollination or autogamy

Strategies

Three strategies that a bisexual chasmogamous flower can evolve to prevent self pollination (autogamy)-
● Dichogamy: Different maturation times of male and female reproductive parts, i.e., pollen and stigma.

• Protandry: Anthers mature earlier than the stigma of the same flower, hence, falling of these pollens on stigma does not ensure pollen tube germination. Example- sunflowers.
• Protogyny: Stigma mature earlier than anther. Example- custard apples.

• Self incompatibility: The phenomenon in which the pollen from the anther of a flower fails to germinate on the stigma of the same flower is referred to as self incompatibility. Example: Potato, tobacco.

• Heterostyly: Development of anther and style at different lengths to avoid easy contact. Example- Primrose, Jasmine, Lythrum