It turns out that’s not a good way to do things at all, but calling that arbitrary and nonsensical is pretty harsh to every naturalist from Aristotle to Linnaeus and on into the 1800s…and if you want to recognize fungi as non-plants, I think into the 1900s too. Just because we have learned better doesn’t mean it was senseless.
Flora seems like a pretty good word for the third category I said above. 
