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 again.
There are others - many others!
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.
Something 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! Plats 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 there!
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 style."
By David Hughes