Understanding Pollination in Closed Flowers: Cleistogamy Explained

The question asks for the specific term used to describe the process of pollination that occurs within flowers that never open. Let's look at the options provided and determine the correct term.

• Allogamy: This term refers to cross-pollination, which is the transfer of pollen from the anther of one flower to the stigma of another flower on a different plant of the same species. This process typically occurs in open flowers and requires external agents like wind, water, or animals.
• Cleistogamy: This term is derived from Greek words where 'cleistos' means closed and 'gamos' means marriage. Cleistogamous flowers are those that remain permanently closed and never open. Pollination occurs within the closed bud. In these flowers, the anthers and stigmas mature at the same time and lie close to each other, ensuring self-pollination as the pollen grains are shed directly onto the stigma. This mechanism guarantees seed production even under unfavorable conditions for cross-pollination.
• Herkogamy: This refers to a structural or mechanical barrier within a flower that prevents self-pollination. Examples include the stigma being located far from the anthers, or the presence of physical obstacles between them. This mechanism promotes cross-pollination.
• Dichogamy: This is a mechanism where the male (anthers) and female (stigma) reproductive parts of a flower mature at different times. This temporal separation prevents self-pollination and encourages cross-pollination. It can be protandry (anthers mature first) or protogyny (stigma matures first).

Based on the definitions, the term specifically used for pollination that takes place in closed flowers is Cleistogamy. In cleistogamous flowers, self-pollination is the only possibility because the flower never opens to allow entry of pollen from other flowers or release pollen for cross-pollination.

Therefore, the process of pollination occurring within closed flowers is correctly termed Cleistogamy.