Do plants really have their own secret language?

From the way Native American healers wait for a plant to tell them how to best use it for medicine, it seems those attuned to nature believe plants talk to each other…and to us. Today, there is a growing body of evidence to support this traditional belief. 

According to Richard Karban, professor of entomology at the University of California, Davis, and author of Plant Sensing and Communication, plants produce many different chemical signals in response to their environments. These signals allow plants to communicate with each other.

How do plants communicate?

One way plants signal each other is through the air. For example, we’re all familiar with the smell of fresh-cut grass, right? Well, that smell comes from chemicals released by grass when attacked by a predator—the lawnmower. Other plants pick up these airborne signals and adjust their internal chemistry in response. 

In a study where sagebrush leaves were deliberately clipped with scissors or damaged by insects, scientists found the damaged branches and bushes around them were eaten less by insects when compared to intact branches. These findings suggest the undamaged branches received a warning signal from the damaged branches and beefed up their anti-insect defenses.

The sagebrush’s airborne messages also increased the likelihood of seedling survival and allowed adult plants to produce more new branches and flowers. Even fanning the air from the clipped plant toward another plant made the second one more insect-resistant. Amazing! And this study is just one of many showing that plants send and receive airborne signals and change their chemistry accordingly. 

In addition to communicating through the air, plants talk to each other underground. For example, a 2018 study on corn seedlings found that the plants secreted a compound through their roots and into the soil to communicate information about the proximity of other plants. 

Another study found that the roots of many plants—including trees—are colonized by a complex communication network of fungi, known as mycelial or mycelium networks, that help them detect whether they are surrounded by strangers or their kin.

What do plants say?

Sometimes plants communicate to avoid competing for resources, as was apparent with the corn seedlings. 

“If we have a problem with our neighbours, we can move flat,” Velemir Ninkovic, lead author of the corn study and an ecologist at the Swedish University of Agricultural Sciences in Uppsala, told the Guardian. “Plants can’t do that. They’ve accepted that, and they use signals to avoid competing situations and to prepare for future competition.”

Plants also communicate to warn each other. For example, the study that identified the network fungi used for communication found that plants used it to send warnings about impending insect attacks to their neighbors. 

So are plants conscious? Well, Peter Wohlleben, forester and author of The Hidden Life of Trees: What They Feel, How They Communicate, seems to believe so. Because of his research, Wohlleben believes that trees are highly social and sensitive beings who communicate to convey friendship and build community. Wondering if this means forests are the original social network? Well, “some are calling it the ‘wood-wide web,” Wohlleben told Smithsonian Magazine in 2018.

Why is plant communication important?

Scientists who study plant communication are hopeful that unlocking the secret language of plants could benefit humanity. Imagine, for example, if farmers could listen to their crops and adapt their agricultural processes to help plants better defend themselves against pests without using chemicals. 

Regardless of whether we’re able to harness the power of plant communication, I hope we all do our best to hear the messages they convey. The relationship we humans have with the plant world is deep and ancient. But it’s not nearly as ancient as the relationship these plants have with each other. Nevertheless, if we listen closely—with open hearts—we may learn from their wisdom.

References:

Shiojiri, Kaori et al. “Airborne signals of communication in sagebrush: a pharmacological approach.” Plant signaling & behavior vol. 10,12 (2015): e1095416. doi:10.1080/15592324.2015.1095416

Karban R, Yang LH, Edwards KF. Volatile communication between plants that affects herbivory: a meta-analysis. Ecol Lett. 2014;17(1):44-52. doi:10.1111/ele.12205

Elhakeem, Ali et al. “Aboveground mechanical stimuli affect belowground plant-plant communication.” PloS one vol. 13,5 e0195646. 2 May. 2018, doi:10.1371/journal.pone.0195646

Babikova Z, Gilbert L, Bruce TJ, et al. Underground signals carried through common mycelial networks warn neighbouring plants of aphid attack. Ecol Lett. 2013;16(7):835-843. doi:10.1111/ele.12115