As a rule, cultivated vines are monoecious (male and female flowers on the same plant), whereas wild vines are dioecious (separately on different plants). The cultivated monoecious vine has hermaphrodites (hermaphrodites), which means that the male and female sexual organs are united in one flower. The all-female wild vines have played an important role in the development of the grape varieties. They were dependent on cross-pollination and at best they were fertilised by another grape variety, which ruled out inbreeding problems. When a grape seed germinated to form a seedling, a new grape variety was then created by this natural crossing. In the case of self-insemination (self-pollination), negative inbreeding effects result in the majority of cases in fewer offspring. Nature has protected itself from this, so to speak, by dioeciousness or self-sterility. This is because fertilisation with foreign genes leads to positive heterosis effects (changes compared to the parents) in the offspring.