Greetings,
I've noticed a few discrepancies in the database at the species/variety/form level. I'm asking for your input as to the source database for review, non-cultivar level. The Plant list seems to be the largest and primarily references Kews WCSPF.

http://www.theplantlist.org/tp...
http://apps.kew.org/wcsp/qsear...

ITIS seems less complete: http://www.itis.gov/servlet/Si...

ATP database: http://garden.org/plants/brows...

I've cross posted this request to the Plant Database forum and request you post all comments there.
The thread "Cypripedium in the database" in Plant Database forum

I am not sure if I understand your question. I usually consult the Kew World Checklist as you did also.

Hi Ursula, Checking with the enthusiasts. Kent gets into it a bit in the Plant Database forum. Please take a look.