How Plants Talk to Each Other Through Underground Electrical Signals

In 1983, two independent research groups published studies showing that undamaged plants near damaged ones produced chemical defenses even without direct contact. The idea that plants communicate was dismissed as fringe science. Four decades later, the mechanism has been largely identified — and it involves electrical signaling more sophisticated than anyone expected.

Action Potentials in Plants

Plants generate action potentials that travel through their vascular tissue at measurable speeds — typically between 1 and 40 millimeters per second, slower than animal neurons but functionally equivalent. When a caterpillar damages a leaf, a voltage wave propagates from the wound site through the phloem within seconds. By the time it reaches undamaged leaves, those tissues have already begun upregulating jasmonic acid — the primary herbivore defense compound.

The Fungal Amplifier

More recently, researchers have found that mycorrhizal fungal networks — the underground web connecting plant roots across entire ecosystems — also conduct electrical signals. Measurements taken across fungal hyphae show voltage oscillations that correspond with plant stress events, suggesting the forest floor may function as a distributed electrical network, propagating alarm signals across root systems that don’t share direct tissue connections.

What This Means For The Future

Agricultural researchers are exploring bioelectric monitoring of crop fields — networks of electrodes that detect the early electrical signatures of pest attacks before visual damage is visible. In greenhouse settings, this approach has demonstrated the ability to detect herbivory 15–30 minutes before conventional sensors would flag an issue. The forest may have been running this system for 500 million years.

Sources: Hedrich et al., Nature Plants (2016) · Simard Lab, UBC

Credit: Cheng Shi Song on Unsplash