Which of the following mechanisms is NOT employed by flowering plants to discourage self-pollination?
Dicliny
Protandry
Herkogamy
Heterostyly
Heterostyly is a mechanism employed by flowering plants to promote cross-pollination, not discourage self-pollination. In heterostyly, plants have different heights of styles and stamens in different flowers, ensuring that pollination occurs between the anthers and stigmas of the same height present in different flowers. This promotes cross-pollination and helps prevent self-pollination, contributing to genetic diversity. Hence, option 4 is the correct answer.