The fruits of parthenocarpic varieties (some tomatoes and cucumbers, for instance) develop without pollination, so they do not require male flowers or insect pollinators. As a result of this, they also don’t form seeds. Parthenocarpic varieties should be grown in isolation from non-parthenocarpic types to ensure that no cross-pollination takes...
Some hybrid cucumbers are bred to be gynoecious – they bear predominantly female flowers. The purpose is to improve productivity earlier in the season, and for the plants to not “waste” energy producing male flowers. Gynoecious seeds are typically packed with a few seeds of a monoecious (plants with male...