FJVAND00 at edu.uky.ukcc wrote:
: In article <761498578snz at chatham.demon.co.uk>
:ohgs at chatham.demon.co.uk (Oliver Sparrow) writes:
:: >Any roadside in India and the Himalaya will yield M. pudica bushes
: >in prickly abundance. A glance shows why it does what it does: as
: >a feathery light green bush, it is irresistable to cattle. At the
: >first nibble, however, the entire thing collapses into a boring
: >bundle of twigs and the cow browses off.
: >_________________________________________________
:: This is the only explanation I've heard for the Mimosa "behaviour". It would
: suggest that the herbivore(s) under which the closing adaptation evolved (not
: necessarily cows?) browse on the basis of visual stimuli, rather than, say,
: how the plant feels to the mouth. Is there any evidence for this? Does
: anybody have an alternative explanation for the Mimosa adaptation?
: Cheers
: Frank van de Loo.
It is also likely to be a defence mechanism against damage to the
foliage during torrential rain. The laminae of leaves subjected to
this type of mechanical stress can adapt in two ways: one is to be
strong enough not to be damaged (Ficus), the other is to minimise the
area of the leaf and drop the petioles to reduce the angle of impact of
raindrops. The 'sensitivity' of Mimosa pudica is such that it would
effectively change habit when the first few drops of heavy rain hit it.
Tony.
--
Dr. A.J.Travis, | JANET: <ajt at uk.ac.sari.rri>
Rowett Research Institute, | other: <ajt at rri.sari.ac.uk>
Greenburn Road, Bucksburn, | phone: +44 (0)224 712751
Aberdeen, AB2 9SB. UK. | fax: +44 (0)224 715349
