Green sentinels

Did you know that trees have their own networks and mechanisms to protect themselves?

July 14, 2021 01:16 pm | Updated 01:16 pm IST

The Acacia can protect itself from animals. Flickr

The Acacia can protect itself from animals. Flickr

Govind was baffled. His cows had been browsing on the leaves of an Acacia tree just moments ago. But when he led them to another healthier one, they wouldn’t touch it. They did the same with the next couple of trees too. Only when they moved quite some distance away did they begin to eat from an acacia tree. When Govind got home with this story, “The first tree must have warned the others about the cows,” his father mused. “And the others must have given off a poisonous gas. So our cows refused to feed from them.” He was right. Scientists have discovered that Acacia trees emit a gas called ethylene when browsed upon. When this reaches neighbouring trees, it stimulate them to produce substances like tannins that make their leaves unpalatable.

Silver Oak: Signals from the leaves

Silver Oak: Signals from the leaves

In another village stood a Silver Oak. A visually challenged man would sit in its shade every afternoon. One day, he was told to go home immediately. “The leaves of the tree have turned over, exposing the silvery underside. It’s a sure sign of a storm.” The man got home just in time and the tree’s warning had saved the village from much harm.

Cannonball Tree

Cannonball Tree

A Cannon Ball tree with crimson flowers stood in a factory’s compound. On the day when there was a leak in the factory, the tree immediately shed all it leaves. The message was very clear: it could not stand the pungent noxious gas emitted due to the leak. The issue was sorted and the repairs were done. Within a week, the Cannon Ball tree had sprouted tiny pink leaves, painting a pretty picture in the concrete jungle it stood in.

African Oil Palm

African Oil Palm

In another spot, a landowner who owned some forested property decided to grow some African Oil Palms. The fruit could be sold to manufacturers of cooking oil and would fetch him much profit. However the trees wouldn’t grow. “It’s almost as if my teak and mango trees are deliberately subduing these saplings,” he grumbled. He wasn’t wrong. The tree roots in the forest had long strands of fungus growing on them and connecting them all. This is what scientists call “Wood Wide Web”. The fungi helped pass messages from one tree to another. When the alien saplings were planted, the original trees sent chemicals that suppressed their growth through this network.

There are many such secrets about our imposing green sentinels. Don’t ever make the mistake of thinking they cannot communicate. They keep sending secret messages to each other and to their surroundings that we do not know about.

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