Question

Mention two strategies evolved to prevent self-pollination in flowers.

Answer 1

Continued self-pollination decreases the vigour and vitality of a particular race. Thus, flowering plants have developed many devices to discourage self-pollination and to encourage cross-pollination.

1. Dichogamy: Maturation of anther and stigma at different times in a bisexual flower prevent self-pollination.
2. Self-sterility: (or self-incompatibility) - Due to the presence of the self-sterile gene in some flowers, pollen grains do not germinate on the stigma of that flowers. e.g.,- tobacco, potato.
3. Herkogamy: The anther and the stigma are placed at different positions or have a mechanical barrier so that anthers cannot come in contact with the stigma of the same flower. Ex : Hibiscus, Gloriosa.
4. Heterostyly: Styles of the flowers of the same species are in different heights.
5. Male sterility: The pollen grains of some plants are not functional. Such plants set seeds only after cross-pollination.