Gonochorism

In biology, gonochorism (Greek offspring + disperse) or unisexualism or gonochory describes the state of having just one of at least two distinct sexes in any one individual organism. The term is most often used with animals, in which the individual organisms are often gonochorous. Gonochory is less common in plants. For example, in flowering plants, individual flowers may be hermaphrodite (i.e., bisexual, with both stamens and ovaries) or gonochorous (unisexual), having either no stamens (i.e. no male parts) or no ovaries (i.e. no female parts). Among flowering plant species that have unisexual flowers, some also produce hermaphrodite flowers, and the three types occur in different arrangements on separate plants; the plants can be monoecious, dioecious, polygamomonoecious, polygamodioecious, andromonoecious, or gynomonoecious.

Unlike most flatworms, schistosomes are gonochoristic. The narrow female can be seen emerging from the thicker male's gynecophoral canal below his ventral sucker.

Sex is most often genetically determined, but may be determined by other mechanisms. For example, alligators use temperature-dependent sex determination during egg incubation. Good examples of gonochoric or dioecious pollination are hollies, and kiwifruit. In these plants the male plant that supplies the pollen is referred to as the pollenizer.

Gonochorism stands in contrast to other reproductive strategies such as asexual reproduction and hermaphroditism. The sex of an individual may also change during its lifetime – this sequential hermaphroditism can for example be found in parrotfish and cockles.

See also

• Diclinous
• Monoclinous
• Plant sexuality