I am even happy to lump the old, open-pollinated varieties that still appear in seed catalogs today with the rare heirlooms. While such plants may not need preservation today, they could become orphans just as easily as their ancestors. In other words, the next generation will look just like its parent. For example, plant a Brandywine tomato, let some of the fruit mature and collect the seed, process it properly, and store it well. The next year, plant the seed and it will grow another Brandywine tomato.
Seed saving is a simple enough process, and gardeners have been using it for generations.
For example, plant nearly any F-1 hybrid tomato, and go through the steps described above to save seed. The next spring, plant it, and see what happens. The seed may not even germinate, since it may be sterile. If it does sprout, the young plants will probably not have many of the characteristics that made its parent noteworthy. While hybrids have many outstanding qualities, the ability to reproduce themselves is clearly not one of them.