Evan,
I'm still of the mind that some of what are known as different types of A. macrorrhizos may indeed be species in their own right. I don't have the Ph. D. to set it forth in a publication or get recognized for that, but lacking that doesn't change the nature of plants themselves. Anyone with good observational skills and the ability to investigate plants via breeding can find out a lot about them even without a Ph. D. Too bad academia doesn't recognize this.
So for now we are left with whatever the taxonomists wish to call them, until they publish another paper and change their minds! To me, A. plumbea and variants are not A. macrorrhizos. The true Black Mac may be a species but since I haven't worked with it or seen how it breeds, I cannot be certain about that ;yet. Others I have worked with, I can discuss in greater detail. Chimeric plants like A. plumbea "nigra" and the white variegated Mac, IMHO, should not be designated species as they are way too variable for that, not to mention the fact that all A. plumbea types seem to be sterile anyway.
The comments may be the best place to clarify things such as I am mentioning here.
LariAnn
