I'm often confused about proper naming for plants, and I used to think it was just ignroance on my part.
But I'm glad to find out that there are learned, subtle and even scientific reasons for confusion!
In the battle between scientists wanting to fit everything into neat, unique, uniformly-defined and mutually exclusive categories, and plants' desire to defy simplicity, resist resrtictive definition, and be infinitely various in many subtle ways, I think that it's:
Plants 1, Science 0
"Infinite diversity in infinite combinations"