Susan, I don't blame you for being confused. Registration is feted because it is supposed to stop such confusion from happening. Hemerocallis 'Middendorffii' 1946 (vs Hemerocallis middendorffii 1856) is unfortunate and silly. It must have slipped past the censors.
Technically, Middendorffii is a patronym (named for someone) Latinised by adding "ii" (which indicates gender male) to Middendorff, someone's surname.