D.brevifolia, tropical Drosera, D.capillaris, chromosome numbers

Fernando Rivadavia (ss69615@ecc-xs09.hongo.ecc.u-tokyo.ac.jp)
Mon, 28 Oct 1996 13:07:20 +0900 (JST)

Loyd,

> I have grown D.brevifolia for a number of years now. As with
> much of my stuff the original plants were grown from seed
> with the location details 'El Pinar Uruguay' - did you
> collect this stuff Fernando? My experience has been similar
> to Daves in that my plants have persisted after flowering
> also despite setting seed. Hope this helps.

The plants from El Pinar were collected by Randy Lamb (Hi Randy!)
from Canada during his S.America trip in 1991. He sent me plants and/or
seeds (I don't remember) directly from Uruguay. I'm not sure if Randy
was able to cultivate this plant in Canada and if he sent seeds to other
CPers, so maybe the plants you have are from seeds which I sent to Allen
Lowrie a few years ago.
It's very interesting to hear though that these S.American
specimens you have DO grow as perennials, when for me they didn't. So I
guess I must've done something wrong, but at least it proves that this
species CAN grow as a perennial, though in nature it seems to function as
an annual at least in S.America. So here's a question for the gringos, I
mean N.Americans ;-) , who've seen this species in the wild: does
D.brevifolia grow as an annual in the US (not in cultivation, but in the
wild)?

To egilding@lava.net,

>Most of the species of Drosera I've heard about are either temperate,
>subtropical, or highland species needing cold temps to survive well. I live
>in hawaii and most Drosera species will grow(if I'm lucky) for a 'Season'
>then die. I know Hawaii has a native Drosera species but it comes from the
>cool highlands of Kauai and If it were suited for growth at lower altitudes,
>would have spread to other areas on the Island.

In S.America there are numerous Drosera which you could call
"tropical", some of which are perennials and do not even go dormant. Even
in S.America they are often most abundant on the cooler highlands, but in
my opinion this is simply because in the lowlands the vegetation is
usually too thick for them to survive in, excepting coastal habitats and
places which have been deforested. Some species (especialy in the Roraima
Highland region, apparently) can be found both in the highlands and in the
lowlands surrounding the tepuis.
In Australia there are the petiolaris-complex species which could
also be considered tropical, including D.banksii. There are other species
in N.Australia, as well as in tropical Africa and Asia, which could fall
in this category.

Dave and Tom,

Thanks tons for sending Fabio the seeds, hopefully there should be
something interesting for me to see next time I return (hopefully early
next year). I can't wait to see it all, especially this giant
D.brevifolia Barry described! Sorry also if he hasn't replyed yet, he's
passing through a VERY busy phase right now which should end in
mid-January.

Juerg,

Thanks tons for the chromosome numbers and the references!!

>To Jan (hi!): I think due to the difference of D. roseana (6) and D.
>paleacea (10) the first named is not to be considered as a subspecies of
>the second named taxon, particularly as they even have no common basic

I'm not so sure we can put too much value in the chromosome
numbers found in the pygmy Drosera (subgenus Brysatrum). They vary too
much, showing that the genomes in this subgenus are suffering constant
change, with many chromosomal rearrangements. I wouldn't be surprised if
in the future it was found that populations or individuals of the same
species may have different chromosome numbers. Maybe that explains why
they reproduce so well by gemmae (assexually) but apparently not as well
sexually. Other kinds of study, like chromosome banding, might be better
to show possible relationships between taxa of Subgen.Bryastrum.

Best Wishes to All,

Fernando Rivadavia
Tokyo, Japan