I was once in a fascinating argument/discussion with a group of knowledgable orchid people, including no-less than Dr Phillip Cribb - of whom you woill have heard/read etc. I think we were on the subject of the Paph victoria-regina, chamberlanianum ,liemanianum etc group, and I was able to say that I grew ( still have) a plant which is from a division from the original discovery importation etc of chamberlainianum ( how, is another story ) and that reading his words on the subject, and his keys for separating the species, I could not make any sense at all. Now we get to the key bit ; he (Cribb) accepted that "the whole concept of speciation simply does not work very well with orchids".
Incidentally after wading through a lot of recent stuff about the evolution of man, I come to the same conclusion with animals, at least Homo species. But its a great talking point.