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 place. If it does, the parthenocarpic fruits may develop seeds.