Green Striped Cushaw, Japanese Pie, Silverseed Gourd, Tennessee Sweet Potato, and White Cushaw. Pumpkins and squashes do not cross-pollinate with cucumbers, watermelons or citron. Watermelons and citron both belong to the same genus Citullus and, therefore, will cross-pollinate each other. Muskmelons and Casaba melons will cross since they are both in the same genus Cucumis and also in the same species melo. The Pollination Process Monoecious plants have both male and female flowers on the same plant.
Dioecious plants have only one sex of flower per plant.
Both monoecious and dioecious plants generally require cross-pollination. When a pollen grain lands on a receptive stigma, it forms a pollen tube down the style to the ovary. Male genetic material passes down the pollen tube and fertilizes an ovule. Ovules become seeds and the surrounding ovary develops into the fruit. Male flowers generally appear on the plants several days before female flowers.