The vegetable that would be harvested is different than either parent. The truth is that when plants cross, characteristics are not expressed until the seed produced by the cross is planted and produces a new crop. When field corn and sweet corn cross, however, the kernel appearance and taste are altered the first year.
Plants cross when pollen from one plant is moved to the flowers of another by wind or insects.
Cucumbers do easily cross with other cucumbers. They do not cross with squash, pumpkin, watermelon or cantaloupe. Summer squash easily crosses with other summer squash and with pumpkin. Summer squash doesn't cross with winter squash. Cantaloupes do not cross with cucumbers, watermelons, pumpkins or squashes.