Question

Which of the following mechanism favours self-pollination ?

• A. Protandry
• B. Cleistogamy
• C. Protogyny
• D. Dioecy

Hint:

Mechanisms influencing pollination type:
Favouring Self-Pollination:
Cleistogamy: Flowers never open, ensuring self-pollination (e.g., some violets, peas).
Bisexual flowers where anthers and stigma mature simultaneously and are close.
Favouring Cross-Pollination:
Protandry (anthers mature first).
Protogyny (stigma matures first).
Dioecy (separate male and female plants).
Self-incompatibility.

Answer 1

The Correct Option is B

Self-pollination is the transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant. Certain floral mechanisms promote self-pollination, while others promote cross-pollination.
(1) Protandry: A condition where the anthers (male parts) of a flower mature and release pollen before the stigma (female part) of the same flower becomes receptive. This promotes cross-pollination by preventing self-pollination.
(2) Cleistogamy: A condition where pollination and fertilization occur within unopened, self-contained flowers. Since the flowers do not open, cross-pollination is prevented, and self-pollination is ensured. This is an effective mechanism favouring self-pollination.
(3) Protogyny: A condition where the stigma of a flower becomes receptive before the anthers of the same flower release pollen. This also promotes cross-pollination.
(4) Dioecy: A condition where individual plants are either male (producing only staminate flowers) or female (producing only pistillate flowers). This enforces cross-pollination between different plants. Therefore, cleistogamy is the mechanism among the options that unequivocally favours self-pollination. Cleistogamy