My Science School

Many of us may have heard of or even seen or touched the touch-me-not plant also called the sensitive plant. The moment we touch it the plant quickly folds its leaves inward. It unfolds the leaves when it feels safe enough. The plants have different types of cells that help them fold in response to external stimuli (such as touch, heat light etc.), and unfold.

Scientifically known as Mimosa pudica, the touch-me-not plant spends a lot of energy not during this folding unfolding act. It loses a chance to photosynthesise too. And yet it continues to do this because scientists believe this behavior could have evolves as a response to guard itself against predators, especially herbivores. Closed or closing leaves are assumed to have several benefits. They could make it tougher for animals to detach the leaves from the stems the animals could be fooled into believing the plant is dying or dead and is of no use and the sudden closure of the leaves could shake off insects or even startle herbivores into moving away from the plant while all these are interesting by themselves, something even more fascinating came about in a 2014 study.

A group of researchers decided to study if plants could be “trained” to change their behaviour, and used touch-me-nots for the study. From a height of about 15 cm. test plants in pots were dropped onto foam. This was repeated, and after a point, the plants no longer folded their leaves, perhaps since they did not sense any harm. Intriguingly, even a month after this experiment, the plants remembered to not fold their leaves when the experiment was taken up again Scientists concluded that plants could "learn", a trait usually attributed to animals. And this learning could mean that by not folding their leaves the touch-me-nots could save energy.

Picture Credit : Google