Certain
movements of plants do not result in their growth and are termed as movements
which are growth independent. Hormones bring about various movements in plants
in response to the changes occurring in its surroundings.
On close observation we see that the movement also happens
at a place different from the place of touch. So we conclude, that the
information that a touch has occurred must have been communicated. The plants
use electrical or chemical means to transfer information from one cell to
another as there is no specialized tissue present for the conduction of
information. Then the movement is brought about as the plant cells change their
shapes by altering the amount of water in them. The cells either swell or
shrink and thus change their shapes.
The venus flytrap has a trap which looks and smell like a
flower to insect. When they land on it, they touch a trigger hair which slams
the trap shut and they are then digested by the plant.
Some other
movements seen in plants which are growth independent are-lotus open in the
morning and the tuberose at night, the tentacles on the leaves of the
insectivorous plants like drosera curl inwards at the touch of an insect and
trap the insect, the explosive fruit of balsam plant bursts open at an
appropriate time thus scattering the seeds.
