At 10:09 AM -0400 7/14/98, Carl Pike wrote:
>At the ASPP meeting a speaker (Julian Schroeder, I think) got a mimosa to
>close its leaflets one by one down the line, thus showing the propagation
>of the stimulus. Either I'm stupid or my mimosa is stupid - I can get one
>leaflet pair to close, or a bunch of them more or less together. What's
>the catch?
>>Carl S. Pike (717) 291-3958
>Department of Biology FAX (717) 399-4548
>Franklin and Marshall College Internet C_PIKE at ACAD.FANDM.EDU>P.O. Box 3003
>Lancaster, PA 17604-3003 USA
Hi Carl!
Mine close all four ways (one pair or sometimes even
just one leaflet!), a propagated wave of closures down
the compound leaf, the entire set of leaflets at once,
or the leaflets and the basal pulvini of the entire leaf
at once.
The trick is in getting the stimulus "dose" just right.
The single-leaflet (or opposite pair) close when the
seismonastic stimulus is weak. Slightly greater dose
will give you the wave of closures. More than that and
you get the whole set of leaflets at once. Finally with
a strong stimulus in addition to the leaflets, the
pulvinus at the base of the shared petiole will respond
and lower the entire compound leaf. At the end of this
demo, I usually lift the pot and drop it about 2 cm to
the bench and the whole plant folds up...lots of ahhhhs.
Best Wishes!
ross
________________________________________________________________
Ross Koning | koning at ecsu.ctstateu.edu
Biology Department | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA | fax: 860-465-4479
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