Friends, I have had many inquiries about what is the difference between the ADS Data Bank ($35), and the newly updated RHS Daffodil Register ($78). I conferred with Mary Lou Gripshover and below is her response. However, based on communications I have just received, I believe I will now be sold out of Daffodil Registers. You are welcome to add your name to my waiting list, in case I do end up with a spare.
Mary Lou responds:
The RHS Register has many more cultivars listed, particularly older cultivars. It also lists synonyms, and the databank only list synonyms of cultivars which may still be in commerce, or when–which happens occasionally–a grower lists something in his/her catalog and the name is subsequently not accepted by the RHS. In this case, the databank does list the first name the grower used and says it’s a synonym of the correct name. The RHS Register also lists what is considered to be the first flowering date, which in some cases is many years prior to registration. There’s also a list of species names, those that are considered invalid, preceded by a dagger