Is it correct that Alocasia plumbea has been reclassified as A. macrorrhizos? Is there much debate?

I checked on the Kew records and found this entry

Alocasia plumbea Van Houtte, Fl. Serres Jard. Paris, II, 11: 93 (1875). This name is a synonym of Alocasia macrorrhizos (L.) G.Don in R.Sweet, Hort. Brit., ed. 3: 631 (1839).

Also, the IAS doesn't have an entry for A. plumbea on its list. Haven't seen any discussions on the issue.

Hi Zig, Did you see the Tropicos listing, same as Kew WCSP. http://www.tropicos.org/Name/2...
They reference the "Flora of China Editorial Committee. 2010." Kew indicates some don't accept it. Do you grow either?

I have the "standard" A. macrorrhizos but not the one called A. plumbea. Since A. plumbea was described in 1875 there's probably been a lot of disagreement, and will probably continue to be for another 140 years, LOL.

Zig, I was planning on trying 1 or 2 this Spring depending on how successful my overwintering of potted Colocasia goes. Maybe A. plumbea 'Nigra' maybe 'Metallica' and/or a "standard" A. macrorrhizos. Is A. plumbea 'Nigra' now properly A. macrorrhizos 'Nigra'?

Evan, there's so much variation within species, and so much hydridisation going on I would hesitate to make any claim. But logically I would suspect it could properly be named A. macrorrhizos 'Nigra'. (By the way, despite my wording, I'm not a lawyer, LOL.)

LOL Zig. Imagine 140 years from now a room full of Aroid taxonomists each with a personal translator and lawyer.

In my experience, "A. plumbea" is sterile - the inflorescences produce no pollen. A. macrorrhizos types I've worked with, even such different ones as A. portei, all produce viable pollen. To me, sexual reproduction is a given for a plant to be considered a species. Since "A. plumbea" cannot reproduce itself sexually, it must be either the result of a chance fatal (sexually) mutation or it must be a natural or artificial hybrid.

There is a true A. macrorrhizos "nigra", the true Black Mac, and it is not the same as "A. plumbea". I've gotten some seedlings from crosses last year that are possible throwbacks to the Black Mac, having totally dark leaves and petioles. Unlike "A. plumbea", which is a chimeric plant, the coloration in the true Black Mac is "all over" and completely uniform.

LariAnn
Aroidia Research

Hi Lari Ann,
I think I found some pics of the true Black Mac and I see what you mean about the difference. Does the sterility of A. plumbea suggest a very vigorous plant if a natural hybrid?

Questions re: terminology.
You've placed "A. plumbea" in quotes. Because it's no longer an accepted species?
You've placed "nigra" (A. macrorrhizos "nigra") in quotes and lower case. Because it's a natural variation?
Is this typical convention? With folks growing and selling these plants how should the DB address them?

Thanks,

Evan,

I put A. plumbea in quotes because I do not believe it to be a true species. I cannot state that botanical academia agrees with my assessment; however, my assessment is based on actual field studies involving cross pollination. If sterile plants can be considered true species, then the species problem, which is a fundamental weakness in the foundation of the theory of evolution, is worse than I thought!

The convention for varieties of a species is that the varietal name should be in single quotes, not double, and the variety, if valid in terms of the ICNCP (aka Cultivated Plant Code) should start with a capital letter ('NIgra', correct; "nigra", incorrect). However, since I do not know if nigra is a valid variety according to the ICNCP, the distinction may be spurious at this point.

In my experience, A. plumbea is no more or less vigorous than the A. macrorrhizos types I've grown. I'm a little more inclined to believe that the plant is a sterile sport rather than a natural or artificial hybrid.

LariAnn
Aroidia Research

Thanks Lari Ann,
A. plumbea is considered a syn. of A. macrorrhizos by both Kew and Tropicos. I don't find reference to 'Nigra' or a subtaxa nigra except on plant sales sites and there are plenty of those. One exception is the USDA plants database and they're usually very slow to update. One common name you find often is Metallic Taro.

Edit:
What I'm getting at is what do we call this distinct, sterile A. macrorrhizos variation (both "A. plumbea" and "A. plumbea nigra") now?

P.S. Your Alocasia 'sarawakensis Dark' (or is it new A. macrorrhizos variant) is amazing.

Does anyone know if Alocasia macrorrhizos 'Metallica' and A. plumbea 'Metallica' are the same variation of A. macrorrhizos? Are they naturally occurring or of horticultural origin? Any photos of an inflorescence would be appreciated.

Evan,
In my experience, having seen blooms on the plumbea, the 'sarawakensis dark' and macrorrhizos types, I can state with confidence that the first two have similar inflorescences which are more similar to something I would expect from a cross between A. sarawakensis and A. macrorrhizos. Neither of them is like a true macrorrhizos inflorescence. So it may be that my 'sarawakensis dark' actually has some sarawakensis genes in it after all, but so might the plumbea. If so, that might also explain why the two plants are sterile.

To make things more fun, there is a genuine A. marcrorrhizos black type with all black leaves, veins and petioles. I have developed one like that from a cross of several macrorrhizos types, including the "blackstem" mac as one of the parents. However, the black leaves did not come from the "blackstem" mac but from another plant that did not have black leaves, but ones with a somewhat brownish cast.

LariAnn

I received this from an Agristarts co-op as Nigra/Metallica. Maybe it isn't an Alocasia plumbea, after all. We're experiencing extremely high temps. here, so I think it will darken as the weather cools a bit.

It's a beauty Sandi and looks very happy.

Thanks! It's just a pup from the original one (in the database). After the above posts, I'm not sure now that it is correctly ID'd.

Based on LariAnn's explanation and those of others and the lack of a clear definition of A. macrorrhizos (millennium in cultivation?) and, etc. A. plumbea seems to be the easiest way to identify these Sandi. Agristarts is one of the best tc labs too.

Looks like it to me as well Sandi.

Every A. plumbea I've worked with, whether "nigra" or regular, has turned up sterile in my experience. To me, sterility cannot be a hallmark of a true species; otherwise, the whole definition of species is thrown to the wind. Species have to be able to reproduce sexually; if they cannot, then they must be sports or cultivars, not species. IMHO.