Date: Sun, 19 Jul 1998 19:35:55 PDT From: "Fernando Rivadavia Lopes" <fe_rivadavia@hotmail.com> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2406$foo@default> Subject: A Drosera tentacle speed science experiment
To all Drosera lovers,
Here goes a survey for all Drosera admirers. The most interesting
answers get to be included in the master thesis I'm writing up at the
moment and maybe future papers, with your name included obviously.
Here's the situation. Several years ago, at the beginning of my CP
interests, when I would spend whole days playing with my few plants
until they literally died, while poking around one day I accidentally
discovered that if I stimulated the large tentacles on the apex of the
D.burmannii leaves, these would visibly bend over onto the lamina, maybe
as quickly as 3-4 seconds. This fascinated me since it was the only
Drosera I knew where you could actually see trapping movement happening
before your very eyes.
I don't know how many of you have noticed this, but I imagine I'm not
the only one since D.burmannii is a very common species among CPers
.... WOW!!! We just had an earthquake here!!!! Scary one too, since it
hit all of a sudden! Oh well, wasn't too bad, only around 4 on the
Richter scale, part of everyday life in JAPAN!!! Life goes on again....
Anyways, where was I? OK, about these giant D.burmannii tentacles, they
are shaped differently from other tentacles too, it's not just the size.
The stalk is flat, its base is wide, thinning towards the apex where
there is a rectangular-shaped, and not the usual round, gland.
A few years ago, for the first and only time, I was able to get
D.glanduligera to germinate, flower, and set seed. For those of you who
have been fortunate to see this small jewel alive, it has beautiful
yellowish rosettes and red flowers.
One thing that immediately caught my attenton in this species was its
similarity with D.burmannii in leaf shape and color. It also had the
large apical tentacles on the leaves, only larger. I decided to test
their speed, as I'd done for D.burmannii, and WOW was I surprised! They
wouldn't bend over towards the lamina, slowly, but visibly like in
D.burmannii. They simply SNAPPED over onto the lamina, like a VFT trap
closing shut!! I was completely stunned! I couldn't believe my eyes and
spent hours toying with the poor plants. But since I'd never read
anything about this amazing speed of the D.gladuligera tentacles, I
assumed it was something widely known among CPers, like the VFT trap
speed, and thus redundant.
This lasted until a friend of mine in L.A., Ed Read (Hi ED!),
breathlessly started telling me about this amazing discovery he'd made
with D.glanduligera, how its tentacles are lightning fast....HEY! I know
this story! It was sad to see him wind down so quickly as he asked "You
know about it?", and that's when I realized I'd possibly stumbled onto
something that no one (or few people) had noticed yet.
Since then I've been paying attention to these large tentacles on
Drosera and have seen them on several other species, including
D.sessilifolia (almost a twin of D.burmannii) and a new species from
Brazil, among New World Drosera, and on D.pauciflora, D.zeyheri,
D.esterhuysenae (or was it D.curviscapa?), and maybe a few other
S.African ones.
When I was in S.Africa last year, I saw live D.pauciflora for the first
time and was surprised at how much they also resembled
D.burmannii/D.sessilifolia/D.glanduligera. I tested its similarly large
outer tentacles and sure enough I could see them bending over, at about
the D.burmannii/D.sessilifolia. Later I read an old CPN article by Peter
D'Amato (Hi Peter!) where he described this. So I know at least one
person had seen it before too.
Now my question is (are!), how many Drosera species have these
tentacles and are they always capable of moving at least at a visible
speed when stimulated mechanically? I know most of the New World species
pretty well, so my question goes mainly for African species.
If not too much trouble, I'd like to ask those of you who grow African
Drosera, such as D.aliciae, D.slackii, D.trinervia, etc. to go to your
plants and check for two things.
First, if they have these large tentacles on the tips of the leaves.
They are longer than all the rest, the stalk of the tentacle is flat and
with a wide base where it is attached to the leaf, narrowing towards the
tip, which is a long rectangular shape and also flat.
Second, IF your plant has this type of tentacle, get a toothpick and
stroke it a few times on the rectangular head and wait to see if
anything happens, if there is any visible movement. I find the tentacles
move faster the hotter it is, so try this sometime around noon, or when
the sun is strong.
I'd sure appreciate some feedback on this (which Drosera species have
these large apical tentacles and if they are always capable of visible
movement).
THANKS!!!
Fernando Rivadavia
Tokyo, Japan
P.S. This reminds me of a paper I recently got a hold of (at the Bonn
ICPS meeting) by Seine and Barthlott (from the Bonn Bot.Garden) about
the morphology of Drosera tentacles. Although they surveyed a huge
number of species, the results do not seem to be of much taxonomic
importance for the genus. Interestingly, D.glanduligera had unique
tentacles. In these large apical tentacles, the gland at the tip is
actually elevated
.......... EARTHQUAKE AFTERSHOCKS!!!!..........
elevated on a short stalk over a flat disc at the tip of the tentacle.
So the gland is floating free, except for that narrow connection. I'm
sorry if it sounds like I'm on drugs, but I can't help seeing an analogy
to the mobile base of the VFT trigger hair! Could this be the triggering
mechanism which causes the D.glanduligera tentacles to snap over the
lamina so quickly? Are they morphologically analogous? Would this
explain why this unique tentacle structure is only found in
D.glanduligera, which is the only Drosera (known) that has such amazing
tentacle speed?
This archive was generated by hypermail 2b30 : Tue Jan 02 2001 - 17:31:34 PST