I was once asked to provide vouchers (pressed flowering material) of the
Earlham Hybrids I had to the RHS Herbarium but I felt I had to decline to do
this due to the lack of provenance for any of those I had in my collection,
and I wouldn't want the RHS Herbarium to be full of hopefulls. That said,
many, as you're well aware, are very beautiful garden worthy plants so it
shouldn't put anyone off growing them, it's just that there's a need never
to assume with some of the older ones. In my mind I personally feel that
where older heirloom varieties / hybrids cannot be absolutely proven true to
type they should be marked appropriately when offered and to potentially
improve trading standards if nothing else.