Xanthosoma (fwd)






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Date: Thu, 14 May 1998 17:47:07 -0500
From: Eduardo <eggon@guarany.cpd.unb.br>
To: aroid-owner@mobot.org
Subject: Xanthosoma

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Sender: Eduardo <eggon@guarany.cpd.unb.br>
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=B4 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).=20
    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.=20

Best wishes,=20

Eduardo.


Bob Riffle wrote:
>=20
> 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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