In answer to your question regarding F1 hybrids.
Crossing specific parent plants produces a hybrid seed (plant) by means of controlled pollination. To produce consistent F1 hybrids, the original cross must be repeated each season. As in the original cross, in plants this is usually done through controlled hand-pollination, and explains why F1-seeds are so expensive.
It also means that if you save the seed you have no control of what plant will develop. So they only grow true to the variety you have bought the one time - as the parent plants have to be cross pollinated by hand each year!