Quote:
Originally Posted by Darkman
Having read all that I stand by my premise that the external stimuli of bright sunlight, which could cause sunscald, results in the plant, thru yet undetermined methods, moving ions that have been proven to effect the turgor of certain cells which allows the leaf to fold. This is supported by the fact that leaves will fold if the plant suffers a severe water loss from soil dehydration but not reliably with less than severe water loss and additionally the leaves fold when there is no dyhydration and soil conditions are hydrated fully. This has been documented thru the use of sophisticated and reliable instrumentation that are not known to effect the test results thru variances in their own operating parameters.
I think the banana is smart enough to know when it needs to protect irself from extreme sunlight.
That's my story and I'm sticking to it!
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The problem with your hypothesis is that the first poster's plant was folding its leaves in indirect sunlight. The stomatal guard cells respond to atmospheric moisture by closing if it is too dry. My guess is that the leaf folds up to conserve water. The air on the inside of the folded leaf should be more moist.