Plants can be anaesthetised. When the sensitive Mimosa pudica is touched its leaves fold up, and in 1878 the French physiologist Claude Bernard anaesthetised the plant using ether, preventing the leaf movements. Since then other plant movements have been anaesthetised – but how these drugs work has been a mystery.
Though plants do not have nerves, they can send rapid electrical signals remarkably similar to nerve impulses. Touching a trigger hair on a Venus flytrap fires off an electrical signal that tells the trap to snap shut.
A recent study anaesthetised flytraps with ether, blocking the electrical signal and trap movement. Although the flytraps were paralysed, the trigger hairs of adult plants remained touch-sensitive.
The key to this puzzling behaviour is a gene that codes for a glutamate receptor found only in the adult flytrap trigger hairs. In animals, glutamate is a chemical that passes messages between nerves, and in the anaesthetised flytrap the glutamate receptor was blocked, jamming the electrical signals and trap movements.
So even though plants are clearly very different from animals, they share some features of a nervous system that could shed more light on how anaesthetics work in animals and humans.