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How does cleistogamy allow certain plants to self-pollinate?

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A honeybee collects pollen from the yellow stamens of a pink and cream honeysuckle flower against a blurred green background. — pollination Common carder bumblebee (*Bombus pascuorum*) pollinating a honeysuckle (*Lonicera* species) flower.

Cleistogamy is a reproductive strategy in which certain plants produce specialized flowers that never open. By remaining closed, these flowers ensure that self-pollination occurs within the floral bud, as the pollen is contained and transferred to the stigma without exposure to the external environment.12

This mechanism serves as an extreme method for guaranteeing reproduction, particularly when conditions are less favorable for the plant's typical, showier blossoms. For example, in some species of violets (Viola), cleistogamous flowers develop after the initial flowering season, allowing the plant to augment its population even when environmental factors might hinder cross-pollination.12

While this process limits genetic variability by relying on self-fertilization, it provides a reliable survival advantage by ensuring seed production when animal pollinators are scarce or when the plant is well-adapted to its specific habitat.1