New Study Announces that Plants Sound an Alarm When Thirsty or Injured
But that's only the most recent evidence that there's far more to plants than we ever imagined
Hiya!
If there’s one craze I can get on board with right now, it’s plants. If you’ve read much of my writing, then you know I’m a plant lover. I have, like, thirty or more houseplants I’ve collected over the last couple of years. The only issue I have is running out of space to put them. But you know what? It’s a good problem to have. Plants just have so many benefits, and as far as I’m concerned, we owe everything to them.
This is why, despite fears about global warming, there is at least one benefit— we’re finally focused on learning more about nature and appreciating it rather than disregarding and abusing it. Finally, brilliant minds using advanced technology are radicalizing what we know about plants. Like the study I’m telling you about today, in which researchers captured recordings of plants “crying” when thirsty or injured.
The Study
The study appropriately titled, “Sounds emitted by plants under stress are airborne and informative,” was published in the journal Cell in March 2023 by a team of teachers at the School of Plant Sciences and Food Security, Tel-Aviv University in Tel-Aviv, Israel, was led by Lilach Hadany.
Hadany and her colleagues put tomato (Solanum lycopersicum) and tobacco (Nicotiana tabacum) plants in boxes decked out with small microphones, which were sensitive enough to pick up sounds we humans can’t hear. They also created a machine-learning model to determine whether a plant was stressed from a lack of water or from being cut with 70 percent accuracy.
To their amazement, the tech captured ultrasonic popping sounds emitted by the plants at about 20–100 kilohertz. The noise is too high-pitched for us to hear, but animals like mice, bats, and moths likely can. The plants also made noises more frequently when they were cut or thirsty. Considering their results, the team wondered if the audio monitoring of plants would work beyond the lab and be applied to horticulture and farming.
So they tried it again, but this time in a greenhouse while also using a computer program to block background noises from interfering. Once again, the microphones picked up the plants’ sounds of distress.
While exciting, this study is only the latest by the group. They’ve conducted previous research showing that the tobacco and tomato plants aren’t the only ones to emit a sound when stressed. Other plants make sounds when they are thirsty, too, including corn (Zea mays), Wheat (Triticum aestivum), and wine grapes (Vitis vinifera).
An article in Nature about the research points out an intriguing question. How, exactly, are the plants making these noises — or any noise at all — considering they don’t have lungs or vocal cords?
But… How?
Thankfully, the Nature article includes Hadany’s leading theory to explain how plants create these popping sounds when stressed. Hadany thinks a particular part of a plant, called the xylem, is responsible for making the noise. She explains in the article that xylems are “the tubes that transport water and nutrients from their roots to their stems and leaves.”
The article uses the example of a straw. When sucking water through a straw, surface tension holds the water together. It’s the same basic thing for a plant. While a straw delivers a beverage from a container to our mouths, then down our throats and into our digestive tract, xylems deliver water and nutrients from a plant’s roots to the rest of it.
Additionally, similar to how carbonated beverages make a popping or crackling sound when bubbles pop in a straw, air bubbles popping in a plant’s xylem would also make a noise. Not to mention, bubbling is more likely to occur when a plant is stressed. However, as Hadney says, more research is needed to know for sure.
Not the First Time
Hadany’s theory is basically the same as another one used way back in 2013, well before the research we discussed today when a team of French scientists found that thirsty trees also release ultrasonic noise caused by sap bubbles forming and popping in their xylem. Air bubbles block the water flow for drought-stricken trees, and while the occasional bubble is no biggie, too many can kill a tree.
As exciting as the team’s research is, it’s not the first time experts discovered that plants communicate. A mycology lover named Noah Kalos — better known as MycoLyco on TikTok — is an online influencer who gained his audience by recording the otherworldly sounds fungi like mushrooms make when he connects them to synthesizers.
Then there’s the Greenhouse Silent Disco I told you about a while back. The 23rd Triennale Exhibition of Decorative Arts and Modern Architecture at the tail-end of 2022 allowed visitors to experience plant communication. The exhibit’s creation used LED lights connected to a computer system that translated plants’ reactions to stimuli such as atmospheric conditions, any needs they might have, or even someone’s presence. The system monitored and recorded a plant’s signals, or what it “says,” and then used colored LED lights and sounds to translate it. Talk about incredible.
Still, while experts have known plants communicate with each other and their surrounding environment, Hadany and her team at Tel-Aviv University were some of the first to investigate the meaning behind the sounds. We know plants create sounds, so the next step is to classify them. Doing so could help farmers and horticulture enthusiasts better understand plants’ needs. I mean, just imagine the impact translating a plant’s language could have on agriculture.
Perspective Shift
Many of the headlines regarding these discoveries humanize the sounds plants make. They say the trees are “screaming,” and the plants are “crying,” even though the actual noise sounds closer to slow popping popcorn rather than the wails of a cry or the agony of a scream.
Still, emotional complexities are far more widespread throughout the animal kingdom than we’ve ever been willing to admit. And as we learn more about plants, the idea that they, too, possess some form of awareness, are intelligent, or are even conscious is beginning to seem far less far-fetched.
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