Subject: twining direction of climbers acquired or sun-dependent?

From: [email-masked] (Joop Wolff)
Date: Fri, 03 May 1996 14:57:20 +0200

Repost.

I'm sorry to repost this message right after my recent repost, but my news
server crashed, has been down for most of this week and lost all posts of
the past week. So there is no way for me to find out about reactions
posted.

For some time I've been wondering about the twining direction of climbers
like for instance, Honeysuckle (Lonicera). Honeysuckle always seems to
twine clockwise and some other climbers always twine counter-clockwise.
I checked plant books for the answer, but at most they state the twining
direction, but do not explain the differences or theories on causes of
this spiraling.
Watson and Dallwitz in: "The families of flowering plants: Descriptions
and illustrations" state for instance, matter of factly, as habit of
Honeysuckle: Twining clockwise.
I would like to know whether this is a genetic trait that takes effect
regardless of the hemisphere the plant grows on, or whether it is
dependent on the direction the sun takes in its dayly path (relatively
speaking).  
In the second case the same species of Honeysuckle should twine
counterclockwise on the other hemisphere and behave undecided around the
equator.

Another part of my question is the fact that, as far as I know, there are
more climbers that spiral clockwise than anti-clockwise. Could there be a
coincidence with the fact that there is much more land on this earth on
the northern hemisphere than there is on the southern hemisphere?
That brings me to the hypothesis that, even if the spiralling qualities of
plants are now acquired, regardless of the hemisphere they are planted on,
the development of this quality might have had a connection with the
rotation of the earth. So the hypothesis might then be that climbers that
spiral clockwise originated from the northern hemisphere and climbers that
spiral counter-clockwise originate from the southern hemisphere.

I did get one useful reaction:

In article <[email-masked]>, [email-masked]
(Carolyn Ustach) wrote:

>  As I understand it, there have been no genes isolated which govern the
>  direction of twining in climbing plants.  However, there is the
>  "structural
>  inheritance theory" which states that possibly, these plants are merely
>  following a pattern set up by previous leaves/plants.  How is this pattern
>  setup?  no clue, however, the theory states that genes are not involved.
>  Also, there is another thought that "electrical fields" or some sort of
>  sensing by the plant is going on (plants don't twine until there is
>  something to twine about).  Take home message:  no one knows!  Yet.

The statement "plants don't twine until there is something to
twine about" makes a lot of sense. A pure genetic twining pattern would
yield a twining climber regardless if there is or is not something to
twine around.

I hope someone can point out to me existing research on this subject. Someone
must have brought plants from one hemisphere to the other and watched the
direction of twining.

Joop Wolff ([email-masked])