Do Plants Plants
Are plants more than just vegetables? Do plants have feelings? They
respond to touch; stroke them and they feel it!
All plants are able to
move; it may be the simple (?) movement as the plant
grows, or it can be a rapid snapping shut of leaves on
plants such as the Venus Fly Trap (Dionaea muscipula)!
Another 'mover' is the
Sundew (Drosera). In this case, the leaves have
'tentacles' which close in on the prey once the prey
becomes trapped in the dewy substance on the leaves.
Yet another - and perhaps
the most spectacular - is the Sensitive Plant (Mimosa
pudica). In this case, the foliage simply collapses when
disturbed. Like the Possum (An animal) it plays dead! When
the danger is over, the plant's leaves become normal
There are others - many
Plants do not have muscle
tissue - as we know it - so how do they do it? With the
Venus Fly Trap, it is a matter of hydraulics. Water is
pumped into various portions of the leaves, just like the
bucket on a JCB digger closing up when oil is pumped along
pipes by a motor.
in the plant, instructs it to do this! It is a very clever
'something'; because the instruction is activated when a
trigger hair on the plant's leaves is touched. It is even
more thought provoking, when you realise that the action
does not take place with a single touch. It needs to be
touched twice - or two hairs need to be touched.
This prevents the plant from wasting
energy each time a bit of 'dead' debris falls into its leaf trap. It
needs something that moves, like a tasty fly, or insect. The hapless
insect cannot help but to touch two of the hairs as it tries to escape.
Too late! The interlocking leaves fold over, the insect is digested, and
after a day or so, the leaves open up again to allow the remains of the
insect to be discarded.
Darwin was fascinated by
carnivorous plants, in particular the Venus flytrap (Dionaea
muscipula) and its response touch. He believed that the
way the plant snapped its trap shut indicated the presence
of a central nervous system - such as that of an animal.
Between 1960 and 1970,
Burdon-Sanderson conducted many experiments on the Venus
flytrap (Dionaea muscipula). The first experiment, and
possibly the most remarkably revealing of all, was to
attach electrodes to the surface of the trap lobes in the
hope of recording electrical activity. Similar to how
scientist detec feelings in pther organisms! He found that
each time a trigger hair was touched it fired off a wave
of electrical activity almost identical to the nerve
impulses, or action potentials, produced by animal
neurons. This experiment was carried out on the Sundew and
Sensitive plant - with similar conclusions!
Now with modern day
equipment, plant physiologists are beginning to understand
much more about plant movement. It has been confirmed that
the impulses Burdon-Sanderson detected are indeed action
potentials similar to those in animals, they are also now
beginning to unravel the molecular and cellular reasons of
the ability of plants to respond to touch. In humans - we
call these impulses feelings! this type of feeling is
quite distinct from the emotions that we know as feelings.
Touch sensitive movement
- feeling - is known to occur in over 1,000 different
species of plants. Other common ones are the tendrils of
peas, which curl towards a 'touch', and of course the
twining stems of beans.
Not for one moment are we suggesting that plants have
similar feelings to us humans. Nor are we discounting it! Plants are 93%
water - as are humans - and needs food, drink and air to live. They
reproduce sexually - and also non-sexually, so they have one up on us
It is also interesting to know that a system of
immunity also exists in plants - an immune system! This has been
engineered by plant breeders that have produced varieties that are
'resistant' or in some cases 'immune' from certain diseases that affect
there genetic brothers - and sisters.
What tells them to?
Plants also use their
sense of touch for sex: As the growing pollen tube
penetrates the female's style en route to her eggs, it
"feels" its way along the ridges on the inside of the
style. Using pollen tubes grown in dishes, Tokufumi
Hirouchi and Shozo Suda, of Kobe University in Japan,
showed that pollen grows along tiny ridges etched into the
glass dishes. Similar sized ridges exist in the female
By David Hughes -