In 1997, Suzanne Simard published a paper in Nature showing that trees in a Douglas fir forest shared carbon through underground fungal networks — the mycorrhizal web that connects the root systems of most terrestrial plants. The finding was controversial, widely covered, and ultimately confirmed. What it didn’t answer was how fast the sharing happens, or what triggers it. Those questions are now being answered, and the answer involves electricity.
A series of studies culminating in a 2023 paper from the University of the Sunshine Coast has mapped rapid electrical signaling through mycorrhizal networks in response to herbivore attack, drought stress, and physical wounding. The signals travel at speeds of 1–2 centimeters per minute — slow by neuronal standards, but fast enough to warn neighboring trees before visible damage appears.
The Signal
When a tree is attacked — by insects, fungal pathogens, or physical wounding — it generates a systemic electrical signal that spreads through both its own vascular system and the connected mycorrhizal network. The signal resembles a slow action potential: a sustained depolarization that propagates through the living cells of both the plant and the fungal hyphae. Neighboring trees connected to the network receive the signal and respond within hours by upregulating jasmonic acid, a chemical defense compound, before any physical attacker has reached them.
Forest Bioelectricity Facts
- →1–2 cm/min — speed of electrical distress signal through mycorrhizal network
- →Hours — time for neighboring trees to upregulate defense chemistry after signal receipt
- →90%+ of terrestrial plant species form mycorrhizal partnerships
- →Ion channels identified in fungal hyphae that mediate signal propagation
Are Plants Sentient?
The question is premature but no longer dismissible. Plant electrophysiology — the study of electrical signals in plants — is an active and growing field. Venus flytraps generate action potentials measurably similar to animal nerve impulses. Mimosa pudica transmits wound signals electrically to fold its leaves faster than chemical diffusion could explain. The mycorrhizal research adds a network dimension: not just individual plants signaling, but forests doing something that, at a functional level, resembles a distributed nervous system.
What This Means For The Future
Agricultural applications are the most immediate: monitoring the electrical state of crop root networks could provide early warning of pest pressure or drought stress before visible symptoms appear. Forest conservation could use network electrical monitoring to track ecosystem health at scale. And for basic science, the mycorrhizal electrical network is a natural model for studying how information propagates through large-scale biological systems without central coordination.
Source: Simard (1997) Nature · Elhakeem et al., Scientific Reports (2023) · University of the Sunshine Coast
Credit: Fahim Junaid on Unsplash