The idea that plants communicate by sound has caught on among some scientists and the media 鈥� but there is no solid evidence that it is true, according to a review of published studies.
鈥淧lants are not capable of exchanging information through the acoustic channel,鈥� says at Jean Monnet University in Saint-Etienne, France.
Since as far back as 1970s, scientists have known that plants make sounds under various forms of stress, such as a lack of water or being nibbled by caterpillars. Water moving through plants鈥� vascular tissue results in squeaks and chirps if fluid is scarce, while the rhythmic chewing action and foot movement of herbivores causes leaves to vibrate.
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Several studies have proposed that such sounds might be perceived by neighbouring plants, which might then respond in beneficial ways, such as growing larger or developing chemical or physical defences.
However, Mathevon and his colleagues highlight that these sounds are both very high-pitched and very low energy, so are unlikely to propagate more than a few centimetres.
Plus, there is no known means by which plants could detect such sounds. Even if they were close enough to perceive the clicks, 鈥渢here might be no benefit to responding, or one individual could be eavesdropping on incidental cues produced by another,鈥� says at the University of Missouri, who wasn鈥檛 part of the research.
There have been some studies claiming that loudspeakers generating low-frequency sounds can influence plant growth. This has genuine agricultural potential, says Mathevon, 鈥渂ut plants don鈥檛 make such sounds and can鈥檛 perceive them.鈥�
Instead, the evidence suggests that these responses occur when sounds coincide with the resonant frequencies of the cells themselves, he says. In contrast, a stressed plant鈥檚 squeals are too high to produce such growth-enhancing rumbles.
鈥淭his article provides a welcome corrective to the idea that if a plant produces a sound, it must be using [this] to communicate,鈥� says Cocroft.
鈥淩esearch into plant bioacoustics is in its infancy, and there are potentially fascinating discoveries ahead,鈥� says Mathevon. But he and his colleagues believe that, so far, there is little indication that your houseplants are talking to each other.
However, at the University of Modena and Reggio Emilia, Italy, believes this conclusion may be premature. She points out that plants can communicate using airborne chemicals at levels significantly lower than our sensitivity, and says we need to take a plant-focused approach.
鈥淭he biggest gap in this topic is precisely how plant communication can be experimentally evaluated given its complexity,鈥� she says. 鈥淚t鈥檚 a bit early to dismiss it as fiction.鈥�
New Phytologist
