My personal view is that sometimes lumping is overdone. One of these days someone will give a clear set of rules for separating one (or more) population(s) as a subspecies. I know that some degree of fuzziness is only to be expected in plants, as many are intrinsicly variable. But, to help we poor amateurs understand some botanists decisions, and to get some order into classification, at the very least some clear framework should exist.
I'd hope, as botany is an established discipline, that it does, but it doesn' t appear to be publicly available.
If any professional botanists read this forum, do come out and help me, and maybe others, understand.