The Secret Language of Plants
From the Wizard of Oz to Lord of the Rings, trees have had something to say to us. But as science is now determining, they also have something to say to each other.
A stunning discovery currently unfolding reveals that not only are trees and plants able to communicate, but do so in clearly defined messages. And we’re even learning what they’re saying.
We tend to think of trees as solitary loners with each tree fighting the surrounding ones for sunlight, water, and nutrients. But advances in science, forestry, and ecology are showing this is not always the case. Trees can be very socially connected and work cooperatively among themselves to ensure their survival. And for this to occur, there must be communication. And there is.
Every Species Has a Language
Between the humans, aquatic life and insects, mammals, birds, and plants, Earth is quite the eclectic collective of inhabitants. And while many life forms don’t talk as we define talking, they clearly communicate.
In the insect world, information is conveyed through a series of touches, body-language, and the use of chemical vapors. Bees share information with hive members through their jiggly little dance number and the chemical dispersion of pheromones. Ants release chemicals and use their feelers to convey vital news to the colony. Dolphins and whales converse with pod members through a catalog of clicks and songs. All communicating in their own language.
With certain plants and animals, however, we instinctively know what they’re saying. From the thorn-covered vine quietly warning ‘don’t touch me’, to the paranoid little cat that morphs into a blowfish the instant you make eye contact. Same message, different language. Universally understood.
Are Plants Really Communicating?
Advancements in technology are allowing scientists to listen in on the trees’ communications and even decipher what they’re saying. Trees interface through the release of chemical cocktails containing volatile organic compounds (VOCs) delivered via airmail.
Collectively, these communicative compounds are referred to as allelochemicals or infochemicals. And these aren’t merely random gasses escaping through natural processes, they are deliberate, information-packed chemical texts carrying specific details that vary according to circumstance.
These chemical agents sound the alarm when a tree comes under attack from insects or mammals, and they can distinguish the difference. Studies are revealing that trees talk not only with family members, but even to trees of another genus. Amazingly, these messages can be received and understood by other nearby plants eavesdropping on the message emitters.
These chemical smoke signals can also send out a call for help to the community of arthropods (bugs).
When certain trees come under attack from leaf-chewing caterpillars, they release specific volatile blends into the air to attract parasitic wasps. It’s like a high-tech dinner bell. Through this symbiotic relationship with the trees, the wasps appear and deposit their eggs atop or even inside the caterpillars. The eggs hatch in a matter of days and the invaders are soon dispatched by the hungry hatchlings before they inflict more damage. (Read also: Help Your Plants Help Themselves: Enhancing Natural Defenses)
An Interview with Chemical Ecologist James Blande
Discovering that plants and trees can literally communicate about specific issues really piqued my curiosity and I wanted to learn more. I contacted one of the world’s leading scientists in this branch of study (so to speak) with some questions. He kindly granted an interview.
Professor James Blande is a chemical ecologist at the Department of Environmental and Life Sciences, Environmental Ecology Research Group at Eastern Finland University. Additionally, he is a noted author and the lead scientist on a project studying this phenomenon. Professor Blande also teaches Entomology and as such, is the perfect candidate to discuss chemical communication between species.
Thank you so much for taking time for this interview, Professor Blande. I very much appreciate it.
You’re welcome, Alan, it’s a pleasure to chat with you.
How did you become interested in this study?
That’s quite a long story! I have been interested in the phenomenon of between-plant communication for many years, but first started studying it around 2009. At the time I was interested in the effects of air pollution on chemically-mediated plant-insect interactions. As it turned out, I stumbled upon a whole series of interesting questions and have been exploring plant communication, particularly in the context of air pollution and climate change, ever since.
We know bees and ants employ the use of chemicals for communication, are there similarities between the chemicals insects release and those of plants and trees?
There are similarities between the chemicals released by certain plants and insects. Typically, some compounds released by insects, e.g., sex pheromones, are chemically quite similar to some compounds released by plants. I would say that insect pheromones tend to comprise one or a few compounds in specific ratios, whereas plants would usually have a greater number of compounds from a greater number of compound groups.
Are those the volatile organic compounds known as VOCs?
Indeed, these are the volatile organic compounds, which are constituents of the scent or odors of plants and insects alike.
What are some of those compounds?
There is a massive diversity of VOCs produced and released by plants.
A few. Please.
Among the most common compounds are the monoterpenes and sesquiterpenes, which are typical of many characteristic odors, such as the limonene of citrus and the eucalyptol of eucalyptus. Also, a range of alcohols, aldehydes, and ketones, known as green leaf volatiles, that are released upon tissue damage.
How specific are the messages?
The messages encoded in VOCs can be very specific to the plant releasing the VOCs and also to the stress acting upon the plant. For example, a plant damaged by aphids may release a specific odor that is substantially different to that of plants damaged by herbivores that chew leaves. (Read also: Dealing with Aphids in the Growroom)
How do we know what the plant is actually saying in its messages?
We often look at the responses of plants to particular stresses and can collect and analyze the bouquets of chemicals that they release. The particular odors produced represent information on the physiological state of the plant. Hence if a plant is damaged by a particular herbivore species, we could reasonably expect that the tree is releasing a message that it is damaged by herbivores.
It is then open for detection and action by all other organisms in the community. We can be quite certain about the message being sent by the plants, but the responses of plants and the potential awareness of a threat are less well understood.
What, within tree-to-tree communication, has surprised you most?
I think the biggest surprise was the recent observation we made with Scots pine, whereby VOC exposure elicited increases in volatile emissions, photosynthesis, and some defence-related structures. The extent of the response was far greater than I had expected and the first time the phenomenon had been mechanistically investigated in conifers (plants having cones).
Does air pollution affect their communication?
Our research has consistently indicated that air pollution, and especially ozone pollution, can disrupt plant communication.
Can you touch on eavesdropping by other plants and how they respond?
Eavesdropping is the process whereby a plant detects a VOC cue from a neighboring plant and gains an advantage. It is effectively listening in on a VOC message that appears to be intended for a different recipient, be that a distant part of the same plant or a beneficial insect. Often the response of the eavesdropper is similar to that of either the same or a related plant.
Last question. So, what happens when we do understand their language; tree talk, if you will. Can we then induce them to send and receive the messages we want delivered; Perhaps as a way to increase production or strengthen immunity?
This is exactly what we would like to be able to do. In principle, understanding the language of plants will enable us to promote production of plant defenses or even promote flowering in plants. However, we still have quite a long way to go to be able to do this effectively.
Thank you, professor, I truly appreciate you sharing your time and knowledge.
It was a pleasure to discuss this with you.
