Can plants hear noises?
Héliamphora ©OMP
Plants certainly don't have ears. However, they are capable of reacting to certain sounds in their environment, such as birdsong, the buzzing of bees or the sound of a caterpillar chewing its leaves!
Depending on the case, these sound stimuli can accelerate seed germination, speed up the growth of certain plants, and trigger mechanisms to attract insects or defend against pests. And these reactions are only observed for certain very specific noises that they recognize. They do not react to other sound frequencies.
Researchers have carried out astonishing experiments on plants to demonstrate this. For example, it has been shown that in the presence of the specific sound of pollinators approaching its flowers - whether real vibrations, recorded sounds or even artificially produced sounds of identical frequency - evening primrose increases the sugar content of its nectar by 20% in 3 minutes, to better attract them. The bees are able to detect the difference and take advantage of it!
The buzzing of a specific insect also triggers the release of pollen from heliamphora, a carnivorous plant with a tubular anther.
In other cases, defense mechanisms against insect pests are activated. For example, the sound of a caterpillar chewing on an evening primrose leaf has been shown to trigger the production of defensive molecules. These glucosinolate- and anthocyanin-based compounds are toxic to many bacteria and insects. And the plant can produce them even if only a recording of the sound is broadcast!
