7.8 Under Stress

Normally, plant roots grow preferentially toward areas rich in nutrients — a behaviour known as foraging precision.

A 2019 study tested what happens when the leaf veins are partially damaged — as happens after herbivore attacks. The experiment, conducted on plantain and Japanese cherry trees, showed that 30 days after the damage, the roots no longer grew preferentially toward the nutrient-rich areas.

This suggests long-distance molecular communication between different parts of the plant — and raises a question:

Is this the effect of stress impairing the plant’s ability to explore the soil?

And once again: Is this extraordinary behaviour evidence of intelligence — or an automatic biochemical mechanism?