Vegans, vegetarians and Empaths should not read this...

Plants Really Do 'Scream' Out Loud. We Just Never Heard It Until Now.

https://www.sciencealert.com/plants-really-do-scream-out-loud-we-just-never-heard-it-until-now

It seems like Roald Dahl may have been onto something after all: if you hurt a plant, it screams.

Well, sort of. Not in the same way you or I might scream. Rather, they emit popping or clicking noises in ultrasonic frequencies outside the range of human hearing that increase when the plant becomes stressed. This, according to scientists, could be one of the ways in which plants communicate their distress to the world around them.

"Even in a quiet field, there are actually sounds that we don't hear, and those sounds carry information. There are animals that can hear these sounds, so there is the possibility that a lot of acoustic interaction is occurring," explains evolutionary biologist Lilach Hadany of Tel Aviv University in Israel.

"Plants interact with insects and other animals all the time, and many of these organisms use sound for communication, so it would be very suboptimal for plants to not use sound at all."

Plants under stress aren't as passive as you might think. They undergo some pretty dramatic changes, one of the most detectable of which (to us humans, at least) is the release of some pretty powerful aromas. They can also alter their color and shape.

These changes can signal danger to other plants nearby, which in response boost their own defenses; or attract animals to deal with the pests that may be harming the plant.

However, whether plants emit other kinds of signals – such as sounds – has not been fully explored. A few years ago, Hadany and her colleagues found that plants can detect sound. The logical next question to ask was whether they can produce it, too.

To find out, they recorded tomato and tobacco plants in a number of conditions. First, they recorded unstressed plants, to get a baseline. Then they recorded plants that were dehydrated, and plants that had had their stems cut. These recordings took place first in a soundproofed acoustic chamber, then in a normal greenhouse environment.

By contrast, stressed plants are much noisier, emitting an average up to around 40 clicks per hour depending on the species. And plants deprived of water have a noticeable sound profile. They start clicking more before they show visible signs of dehydrating, escalating as the plant grows more parched, before subsiding as the plant withers away.