dichogamy

Dichogamy is a reproductive strategy in flowering plants in which the male and female functions within a flower mature at different times, reducing the likelihood of self-fertilization and promoting cross-pollination. This temporal separation can occur within a single flower over its bloom period or among flowers on the same plant at different times.

Two main forms are recognized: protandry and protogyny. In protandrous flowers, the male phase, during which anthers release pollen, precedes the female phase when the stigma becomes receptive. In protogynous flowers, the opposite sequence occurs, with the stigma becoming receptive before pollen is released. Some species exhibit partial or overlapping dichogamy, where both phases are present for a period, allowing some opportunity for self-pollination if the phases coincide.

Dichogamy is one strategy among several that reduce selfing, complementing mechanisms such as herkogamy, the spatial separation of anthers and stigma, and self-incompatibility systems. The strength and occurrence of dichogamy vary across taxa and populations and are influenced by genetic factors as well as environmental conditions, including temperature and photoperiod, and by pollinator behavior.

Ecological consequences of dichogamy include effects on pollen flow, mating system evolution, and fruit set. In some species, dichogamy interacts with other floral traits to promote cross-pollination between different individuals rather than selfing, thereby shaping reproductive success and genetic diversity.