Unisexuality or dicliny is a condition in which two types of unisexual flowers are present i.e., staminate (male flower) and pistillate (female flower). The plant may be monoecious or dioecious. This is a device for cross pollination (or xenogamy). Both xenogamy and geitonogamy (i.e. transfer of pollen from anther of one flower to stigma of another flower of either the same or genetically similar plant). Autogamy or self pollination (i.e. transfer of pollen from anther to stigma of the same flower) occurs in bisexual flower.