- Scientists in Japan observed plants sending tiny, mist-like messages to each other through the air.
- This is the first time we've seen visual evidence of plants talking to each other.
That sweet, earthy smell that fills the air after cutting grass is actually a cacophony of screams in plant speak.
Like animals, plants can warn nearby neighbors that danger is afoot. But plants don't use sound to communicate.
They use chemicals that they transmit through the air, which just so happens to smell like freshly cut grass to us.
And for the first time, scientists have captured this fascinating conversation on camera.
When healthy plants received warning messages from damaged plants, they lit up like a light bulb, which the scientists recorded using a special microscope that detects certain chemicals as light.
"This imaging technique is a very powerful tool to tell everybody and to let everybody know that plants are very sensitive," Masatsugu Toyota, a molecular biologist and the lead researcher from Saitama University, told Business Insider.
A silent cry of warning
The types of chemicals that plants use to talk to each other are called volatile organic compounds.
These compounds enter healthy plants through pore-like holes called stomata, and travel throughout the leaf, spreading the information around the plant. You can see the process happening in real-time in the video below:
It's like how your nose can detect invisible scents in the air, which your brain reads as information about the environment, Toyota explained.
For example, if your nose detects a stinky, sulfur-heavy smell, it might clue you into an angry skunk nearby.
Plants, it turns out, are doing the same thing, sending mists of particles into the air to warn their neighbors of trouble, the researchers reported in a paper published in the peer-reviewed journal Nature Communications.
The caterpillars are coming!
Yes, some plants were harmed in the making of this study. However, the researchers did so scientifically.
In one container, they placed plants with some hungry caterpillars. In the other, they had undamaged plants without any predators.
They connected the two containers with an air pump, so that air and small molecules could flow between the containers, but organisms could not.
The unaffected container was filled with genetically altered Arabidopsis, which is a weed-like plant in the mustard family, that glows fluorescently when certain chemicals are detected in the plant.
Toyota and his team set up a microscope to detect this fluorescence as a neon green light, and began filming.
Over time, as the caterpillars began damaging the plants in their container, they saw that the plants in the connected bug-free container began glowing bright green, spreading from the tip of the leaf to the base.
Essentially, information from the air, a message, was passed through the plant, like a game of cellular telephone. The plant might use this information to prepare itself for attack, the researchers theorized in their paper.
Be kind to your plants
Toyota said this communication system is incredibly similar to what we see in animals, but on a cellular level.
The information and method of communication are different. But once plants received the message, it triggered waves of calcium signaling, which is similar to how animal cells communicate with each other.
Even human cells use calcium signaling to talk to each other.
In light of these similarities, Toyota said he wants people to take care of the plants they interact with.
Plants "can sense a variety of stimuli in the environment. They can smell and they can sense touch, and they can communicate with each other. There is no border between animals and plants," Toyota said.
"I really want everybody, especially kids, to understand that plants are very sensitive. Please be gentle to all the plants outside," he said.