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Subject: Xanthosoma
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Sender: Eduardo
Subject: Xanthosoma
Dear Bob,
Unfortunately, I am not aware about someone working with the whole
group. Xanthosoma is one of the ``black holes`` of aroids´ taxonomy, and
researchers seem to be avoiding it. I am describing two new species of
such genus from Brazil, and would love to revise it in a near future
(not so near, because I am currently revising Spathicarpa). I am also
aware that Josef Bogner (from Germany) is describing another new
Xanthosoma, but nobody (as long as I know) is dealing with the genus as
a whole. That is really a pity, because Xanthosoma are real beauties,
and they are also important economically (as food crops, ornamental
plants, etc).
About your question concerning the terminology, basal ribs are the
main nerves of the posterior lobes of the leaf. If you are facing a
Xanthosoma leaf frontally (at least in those species whose leaves that
are cordate or sagittate in outline), you will see a kind of ``Y`` that
are the main nerves of the leaves. They are the thickest nerves and are
very easy to recognise in the upper surface of the leaf. The two upper
``arms`` of the ``Y`` are the basal ribs. When I say that they are
denuded, I am meaning that the leaf blade of the basal lobes are lacking
in a small strech of the nerve, near the petiole insertion. When they
arent denuded, the insertion of leaf blade in the lobe is exactly on the
insertion of the petiole. I know, it is very easy to show, and very hard
to explain (mainly to me, because English isnt my native language!), but
I think you can imagine. If you couldnt do it based on my description in
``crazy English``, e-mail me privately and I can send you a digitalized
drawing of the two kinds of leaves.
Best wishes,
Eduardo.
Bob Riffle wrote:
>
> Oh, Eduardo, DECIDEDLY there needs to be taxonomic research done on
> these things! Do you know of anyone or group who IS working on
> them. It's rather hard to believe that it hasn't already happened
> because of the extraordinary beauty of these things ....
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