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How do plants communicate?

From the Wood Wide Web to the risks of too much human (pre)judgement

Stella Saladino
a story by
Stella Saladino
 
 
How do plants communicate?

Biochemical messages becoming codes to decipher: since the late 1990s, interest in plant communication has been rekindled. But can we truly respect plants only if we make them resemble the best parts of ourselves?

There is no technology so advanced and sophisticated that matches the complexity and perfection of living trees. Perhaps this is why we easily fall into the temptation of thinking that there must be some kind of social communication between plants, some emulation of our intelligence, and the way we relate and communicate.

The Wood Wide Web and mother trees

In 1997, the cover of Nature featured the Wood Wide Web: literally the “wide web of the forest”, a metaphor for the underground communication network between trees in a forest. This metaphor originates from a study1 by Suzanne Simard, formerly a researcher at the Ministry of Forests in British Columbia, Canada.

Until then, it was understood that the roots of certain plants, such as trees, formed symbiotic relationships with particular fungi, the mycorrhizal. In that study, Simard and colleagues demonstrated how the sugars photosynthesised within these symbioses do not stop at the individual plant but are transmitted to other, more distant plants through the fungi filaments (hyphae).

Some sort of “underground highway of communication” that works like the Internet: nodes with more root links, or hubs, provide nutrients to those with fewer, the spokes.

Metaphor upon metaphor, the leap from “hub” to “mother” was a short one, as exemplified by the title of Simard’s bestseller, Finding the Mother Tree (2021).

Over the years, an anthropomorphic narrative has emerged, using terms like “mother” (even though the trees in question are both male and female) to create a sense of closeness and empathy in humans, encouraging them to care about trees by perceiving them as their own kindred.

Trees communicating with each other, caring for each other, and supporting each other in cooperative communities have captured our popular imagination: from James Cameron’s film Avatar (2009) to Richard Powers’ 2019 Pulitzer Prize-winning novel The Overstory (2018).

What if all these depictions showing ecosystems, trees and forests as social beings, talking and communicating with each other, are actually misrepresenting and even harming the cause of their conservation?

Kathryn Flinn’s warning

Kathryn Flinn, a plant ecologist and associate professor of biology at Baldwin Wallace University in Ohio (USA), is known for her challenging positions that counter the romantic idea of trees communicating to cooperate, resembling the best version of ourselves.

Flinn breaks through and definitively shatters that almost magical and fairy-tale atmosphere, in which we like to believe so much, of a profound communion among trees, of a continuous mutual aid always aiming at an ethic of good, as if Nature, to continue with the anthropomorphic metaphor, could never be a wicked stepmother, but only a good mother. 

So, do trees really talk? «Certainly,» Flinn replied in a Scientific American article she authored2. «Plants emit hormones, chemical signals, and defence cues so that other plants can detect these signals and react accordingly by changing their physiology.

However, this does not imply that plants only ever communicate kindly with each other, or that everything is always about cooperation: for example, plants also produce allelochemicals that poison their neighbours. Overemphasising the compassion of trees is misleading and is, in fact, another anthropocentric distortion: the underground terrain of forests is also marked by fierce competition.

Rather than seeing them as objects or as human-like beings, Flynn suggests considering plants in a third way: as plants, living on their own terms.

«Plants are fundamentally different from us,» the ecologist wrote.3 «Mute, rooted, and inscrutable. We must face the challenge of cultivating respect for organisms that are different from us, in their separate and complex bodies, in their sophisticated interactions, in their unfathomable lives».

But why do plants fascinate us so much?

Observing a tree: Francis Hallé’s lesson

Francis Hallé is arguably the foremost expert on primary forests, those last remaining ecosystems that have never been exploited by humans and are at risk of extinction. A renowned French botanist, Hallé employs observation as a key scientific tool for studying forests.

 

During the 1980s, he organised a unique mobile scientific laboratory called the Radeau des cimes, or “the canopy raft”, which he used to study the trees in the jungles of South America, Africa, and Madagascar.

Francis Hallé is the main figure in the documentary Il était une forêt (2013), directed by Luc Jacquet, who won an Oscar in 2006 for La Marche de l’empereur (“March of the Penguins”). The film, which had its Italian premiere in 2014 at the Sottodiciotto Film Festival in Turin, serves as a valuable testament to the last great tropical forests. It offers an extraordinary immersion into this pristine world, where every living being finds its place within the total integration of a singular superorganism.

Hallé is portrayed sitting on a branch, twenty metres above the ground, atop a Moabi tree, one of the forest giants in Gabon, Central Africa. Right from up there, from that angle, his gaze becomes a knowledgeable, attentive observer of non-human intelligence, revealing the true intellectual revolution brought about by observing a tree.

A tree is simultaneously one and many, never to be considered as a “single individual” like a human being, but rather as a colony, a collective entity. A tree can be seen as a modular organism that develops according to its own genetic heritage, depending on its structural complexity and the environment in which it lives.

Observing forests, unveils the incredible world of interdependencies, interrelations, and morphogenesis that plants are capable of. The key lies in the otherness of plants, their profound mystery, and their silent witness to our history, yet central to our survival.

Understanding trees and forests means, in a sense, becoming a tree oneself, reaching those heights, that flexibility, and that ability to be diffuse, modular, vertical, and horizontal simultaneously, changing posture and form to better approach the vegetal beings.

«A tree may seem like a trivial thing, a simple, fairy-tale solution for somewhat naive and pre-modern people who dislike technology. However» asserts Francis Hallé in the documentary, «there is no technology as complex and perfect as that of a tree.»

Artificial Intelligence adds its own code

In this intricate scenario of complex human-non-human relationships, Artificial Intelligence is also taking its first steps, with extremely intriguing applications attempting to create subtle bridges between us and the plant world.

The latest challenge is to find a “companion” for the “world’s loneliest plant”, the Encephalartos woodii (E. woodii). Left alone in South Africa, this ancient species is believed to predate even the dinosaurs and is considered one of the most endangered organisms on the planet.

The University of Southampton has embarked on a research project to prevent its extinction: drones programmed to recognise the plant’s image through AI algorithms are scouring the forests of South Africa to find a “female partner” for the “male” plant.

«I was very inspired by the story of E. woodii; it mirrors a classic tale of unrequited love» said Laura Cinti, the lead researcher on the project, in an interview with the BBC4. «It would be incredible to save this plant so close to extinction through natural reproduction».

The human urge to communicate with plants

Is the profoundly human desire for plants to communicate, to love each other, to have a mate or companion, as happens in our lives, therefore legitimate? Where can it lead us? Towards new fantasies or further distortions? Or can it even lead us to think that plants can also communicate with us, that they want to tell us something, reveal their most ancestral and mysterious secrets?

There have been ongoing debates for decades about human-plant communication, yet to be resolved, illustrating just how urgently humans seek to communicate and be benevolently acknowledged and reciprocated by Nature.

Nothing makes us feel safer than sitting at the roots of a tree, running our hands over its bark. Wouldn’t it be amazing if there was also a response, a reciprocity, a positive correspondence from the plant?

But would the tree really have to (cor)respond? Could it not be that people and trees live in completely different worlds?

And what if, in reality, plants simply ignore us?



  1. To consult Simard’s study, see Simard S. W., Perry D. A., Jones M. D., Myrold D. D., Durall D. M., and Molina R. (1997). Net transfer of carbon between ectomycorrhizal tree species in the field. Nature388(6642), 579–582. https://www.nature.com/articles/41557 ↩︎
  2. For Flinn’s idea on plant communication, see Flinn K. (2021). The idea that trees talk to cooperate is misleading, Scientific American. https://www.scientificamerican.com/article/the-idea-that-trees-talk-to-cooperate-is-misleading/ ↩︎
  3. For Flinn’s idea on plant communication, see Flinn K. (2021). The idea that trees talk to cooperate is misleading, Scientific American. https://www.scientificamerican.com/article/the-idea-that-trees-talk-to-cooperate-is-misleading/ ↩︎
  4. To read Cinti’s interview, see AI helping find ‘world’s loneliest plant’ a partner (2024), BBC. https://www.bbc.com/news/articles/ce99v9z0529o ↩︎

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