Date: Tue, 28 Oct 1997 19:17:45 +0900 From: ss66428 <ss66428@hongo.ecc.u-tokyo.ac.jp> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg4145$foo@default> Subject: D.nidiformis and taxonomy of S.African Drosera
To all,
First of all, sorry to anyone who had messages returned from my server
in the past few days. They had some kind of an overload, but now they're back
on line and you can resend me any returned mails.
About D.nidiformis, I'm amazed Jan hasn't sent in his comments on this
plant yet! :):) Anyways, there is quite a bit of doubt about what it is, but
I agree that it is NOT D.dielsiana. I was gonna mention it in a future post
about the CPs I saw in Africa, but I might as well do it now. I went to the
Magaliesberg Mts., not far from Pretoria and Johannesburg, and found
G.hispidula, U.firmula, D.burkena, D.madagascariensis, D.collinsiae, but not
D.nidiformis.
I can't say if it truly is a species or if it is a hybrid, but one
curious thing I observed is that the form of D.madagascariensis native to the
Pretoria/Johannesburg area is a short-stemmed, stocky plant with large, thick
green leaves. This is VERY different from the form I've seen in cultivation
which has small reddish leaves and forms long delicate stems, BUT not so
different from D.nidiformis, which looks like a weaker, stemless, more
pubescent form of this D.madagascariensis.
I think there is a possibility D.nidiformis could be a hybrid between
the short-stemmed green D.madagascariensis and one of the local rosetted
species, such as D.burkeana, D.natalensis, or D.dielsiana. I did see D.burkeana
and D.madagascariensis growing together at one place, but no hybrids.
It does seem strange to me though that D.nidiformis is so fertile, if
it truly is a hybrid. Is there any Drosera hybrid which reproduces as well
from seeds? Highlighting its fertility, a few years ago I was successful in
crossing D.nidiformis with D.dielsiana, D.natalensis, D.venusta, D.coccicaulis
(the last two considered by Jan to be forms of D.natalensis), and maybe other
S.African rosetted species, I can't remember.
I think it would be probably best, for the moment, to accept
D.nidiformis as a valid name until it can be sorted out, one way or another. It
certainly does not seem to belong under D.dielsiana, especially because the
seeds are fusiform, more like those of D.madagascariensis, whilst D.dielsiana
has ovoid seeds. It would be more comprehensive maybe, Jan, if you put it on
the database as "S = D.madagascariensis X D.dielsiana/natalensis ?".
Still on the taxonomy of the S.African Drosera, I spent quite a while
trying to understand where the borders lay between D.aliciae, D.natalensis, and
D.dielsiana. Between the 1st two, it seems like geography is the main
characteristic separating them while the latter two can supposedly be easily
distinguished by seed and style shape. Considering how variable D.natalensis
seems to be in the wild, its separation from D.aliciae seems very weak and
Obermeyer even mentions in his Flora of S.Africa that "...it is sometimes
difficult to distinguish them in the Eastern Cape where their ranges
overlap;..."
As I said, it is "supposedly" easy to distinguish D.dielsiana from
D.alic. and D.natal. because of its ovoid seeds. I had a hard time trying to
identify a plant in cultivation and in the end could come to no conclusion,
even with the help of another biologist, Robert Kunitz (Hi Rob, if you're out
there!). The plants in question are what I called D.dielsiana for years in
cultivation. They have flat rosettes of reddish spatulate-cuneate leaves, and
the seeds, to my surprise, were neither ovoid nor as fusiform as those of
D.aliciae we had available, which were clearly fusiform to the naked eye, more
than showed by Obermeyer. In fact the 'fusiform' seeds drawn in that paper are
almost ovoid.
As to stigma shape, Obermeyer does mention a few differences such as
spoon-shaped for D.dielsiana, but I am convinced that this is not a
characteristic to bet your horses on, seeing how variable these are in some of
the Brazilian taxa I've been looking into, as Jan knows. And the D.dielsiana(?)
I was analyzing had style shapes more or less intermediate between those
described for D.dielsiana and D.natalensis in Obermeyer. Quite a messy group!!!
And to add more to this confusion, I could see no major differences
between D.capensis and D.ramentacea to justify the separation into different
species. The latter just seems to be a hairier form of the former.
Best Wishes,
Fernando Rivadavia
Tokyo, Japan
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