Plants Emit Ultrasonic Screams When Stressed
Finn's Take· TL;DR- Plants emit ultrasonic clicks when stressed—audible to insects and animals up to five meters away, undetectable to humans.
- Different stress types produce distinct sound patterns; machine learning can identify plant species, stress cause, and dehydration onset before visible damage.
- Findings suggest insects, moths, and mammals may use plant ultrasonic signals to locate hosts for eggs or food sources.
Hidden World of Plant Communication
Your garden may be far noisier than you think. Scientists have discovered that many plants emit faint ultrasonic clicks when distressed, with tomato and tobacco plants releasing bursts of sound when dehydrated or physically damaged . These sounds are as loud as a normal conversation, around 60 to 65 decibels, but occur at frequencies far beyond human hearing .
The ultrasonic noises resemble faint pops or clicks, similar to bubble wrap snapping, and also occur when scientists cut the plants' stems . This means the world around us may be filled with plant noise that goes completely unnoticed . Although ultrasonic vibrations have been recorded from plants before, this is the first evidence that they are airborne, making them more relevant for other organisms in the environment .
Stress Signals and Detection Methods
Stressed plants produced far more sounds than healthy ones, with a single stressed plant emitting about 30 to 50 sounds per hour at irregular intervals . In contrast, healthy plants were mostly silent, with unstressed tomatoes being "very quiet" . Plants experiencing water stress began making sounds before showing visible signs of dehydration, with the number of sounds peaking after about five days without water .
The type of sound varied depending on the cause of stress, and a machine learning system successfully distinguished between dehydration and physical damage while identifying whether sounds came from tomato or tobacco plants . Researchers found that these stressed plant sounds could be detected up to five meters away using ultrasonic microphones .
Broader Plant Kingdom Discovery
Although the study focused on tomato and tobacco plants because they are easy to grow under controlled conditions, researchers also found that many other plants, including corn, wheat, grape, and cactus plants, emit sounds when stressed . The exact cause remains uncertain, though researchers suggest the sounds may result from cavitation, a process where air bubbles form and burst inside the plant's vascular system .
While it's unclear whether plants produce these sounds deliberately to communicate, their existence could have important ecological and evolutionary consequences . Moths and other insects that can hear in the ultrasonic range, as well as mice and other mammals, could detect these noises from as far as five meters away .
Future Implications and Research
Other organisms could have evolved to hear and respond to these sounds, with potential applications including moths deciding where to lay eggs or animals choosing which plants to eat . The findings open new possibilities for understanding plant communication and have potential applications in agriculture for monitoring crop hydration and optimizing irrigation systems .
Scientists are now investigating who might be listening to these plant sounds, exploring responses from other organisms and developing abilities to identify and interpret sounds in natural environments . This research fundamentally changes our understanding of plant behavior and suggests that the silent world of vegetation may actually be filled with constant chatter we've simply been unable to hear.