“What will become of the plants that are not distinctive enough to register and not poor enough to throw away?”
This is the question that all hybridizers find themselves asking at some point. If I remember correctly, Roy Person would let the public come in and dig up all the seedlings that he was not interested in keeping ! This may not be the best approach, but the question is still a dilemma for hybridizers.
My sense is that the best plants for further hybridizing are often not the plants that are most worthy of commercial introduction. Plants for introduction need to be good of course, but sometimes non-introducible plants from the same cross have valuable qualities that the introduced ones might not have, By that I mean good pollen, or the ability to make seeds. Such plants may also have spectacular vigor, or remarkably strong stems. Their flowers may not be remarkable, but they can contain many of the same genetics as the introducable plant has.
I know for myself that I have several plants like this. They will never be introduced, but when combined with other varieties through hybridization their value is proven.
To see more of Han’s hybridizing results, it’s worth taking a trip to Han’s website. While it’s not in English, he shows us the outcomes of his various crosses, not only with tennifolia, but with other varieties as well, and is something that can give the casual observer an idea of what hybridizers are up against, when they have to evaluate the results of their crosses.