Plant Intelligence: Myth or Reality?
In broad terms, the idea of plant intelligence refers to the biological ability of plants to actively perceive and respond to their environment. Plants are not passive organisms: they process information, use complex signalling mechanisms and adjust their behaviour to changing conditions. Whether these abilities should be described as ‘intelligence’, however, remains intensely debated.
In this article:
Sensing the environment without dedicated sense organs
To understand the idea of plant intelligence, it is useful to begin with a simple fact: although plants have no eyes, ears or noses, they can detect an impressive amount of environmental information. Consider phototropism, the growth response to light involving hormones such as auxin, and gravitropism, the response to gravity involving specialised cells and structures, which helps roots grow downward while shoots generally grow upward.
Plants can also respond to mechanical vibrations, including vibrations associated with water or insects. Plant bioacoustics is an emerging field investigating how mechanical waves may function as environmental information, alongside better-established mechanisms involving mechanosensitive proteins and cellular responses.
Plants also detect chemical gradients in the soil through chemotropic responses, allowing roots to respond to changing concentrations of nutrients, ions and other chemical substances.
Together, these sensing mechanisms show that plants are far from passive organisms. A plant can be viewed as a highly distributed biological sensing system, continuously integrating information from its surroundings.
Plant sensing and physiology have been widely explored by French botanist Catherine Lenne, a member of the PIAF laboratory (Integrative Physics and Physiology of Trees in Fluctuating Environments). Her books offer accessible ways to explore the subject further, including Dans la peau d'une plante (2014), Dans la peau d'un arbre (2021) and Vous avez dit biz'arbres ? (2024). Her research publications are also available through the HAL open archive.
Communication, memory and learning
Beyond sensing their environment, plants participate in complex ecological interactions, including those associated with mycorrhizal networks — sometimes nicknamed the ‘Wood Wide Web’. These networks arise from a symbiotic relationship between fungi and plant roots. Research has documented transfers of carbon and nutrients in some systems, as well as changes in signalling and defence responses. Scientists continue to debate how widespread these effects are and how they should be interpreted.
This research has also popularised the idea of ‘mother trees’, referring to older trees that may function as highly connected nodes within some forest networks. Trees also release volatile organic compounds (VOCs), which can act as airborne chemical signals with many ecological functions.
Discussions of plant memory and learning often cite the work of Italian-Australian evolutionary ecologist Monica Gagliano, known for her pioneering and controversial research on ‘plant cognition’. One well-known study involved the sensitive plant (Mimosa pudica), testing whether repeated harmless stimulation could produce a form of habituation. In the 2014 experiment, the plants eventually stopped closing their leaves after repeated harmless drops, and the response remained altered for an extended period. The interpretation of this result as ‘learning’ remains debated.
No scientific consensus on the word ‘intelligence’
Unsurprisingly, the term ‘plant intelligence’ has no consensus within the scientific community.
Some botanists and biologists use concepts such as decentralised cognition or intelligence, while others warn against excessive anthropomorphism. Critics argue that terms such as intelligence, cognition or consciousness may imply capacities associated with nervous systems and that applying them to plants can create semantic confusion. They often prefer expressions such as ‘complex adaptive mechanisms’.
Intentionality is another key question. When a plant responds to an attack, does that response imply awareness, or can it be fully explained by evolved biochemical mechanisms? At present, there is no evidence that such responses require conscious intention.
The debate therefore centres largely on the use of the word ‘intelligence’. Disagreement is often less about whether plants have sophisticated sensory, adaptive and signalling abilities than about how we describe them. Many of those capacities are well-established biological realities, while ‘intelligence’ is still frequently used as a metaphor for biological complexity that science is continuing to unravel. 🙂
To finish, here are three quotations that invite a more philosophical reflection on the subject:
Plants are beings from which we still have everything to learn, yet we persist in looking at them as objects.
From Plaidoyer pour l'arbre (2005) by Francis Hallé (1938–2025), French botanist and biologist.
Calling a plant intelligent is a very human compliment. It can prevent us from seeing what is distinctive about plants: their distributed structure allows them to solve problems in ways that do not require animal-style intelligence.
From Nature et préjugés : Reconstruire notre relation au vivant (2024) by Marc-André Selosse, French biologist and science communicator.
The problem is not that plants lack intelligence, but that we struggle to imagine intelligence without a brain.
From L’intelligence des plantes (2018) by Stefano Mancuso, Italian biologist and researcher.
A quieter perspective that appears when we slow down…
Plant intelligence is not only an idea to analyse; for many of us, it also changes the way we encounter plants. Beyond the scientific discoveries, another door may open — towards a quieter, more attentive relationship with the plant world, one that becomes clearer when we are fully present, receptive and attentive.
Understanding plant behaviour intellectually is one step. Experiencing trees through the body, the senses, the heart and — for those who value it — intuition can profoundly change our relationship with the Living World.
That is precisely what I invite you to explore.
During my forest therapy walks, you are invited to slow down, open your senses and enter into direct contact with trees — making space for what can be noticed beyond words, in the quiet attention that nature encourages.
And for those who want to go further, the spiritual forest therapy training offers a genuine immersion: a form of learning and transmission at the crossroads of scientific knowledge and inner experience, designed to help you guide encounters between people and the plant world in your own way.
Perhaps the pull you feel while reading these lines is simply your own sensitivity responding to the Living World around you. If something resonates, I invite you to follow that thread — to come and walk, breathe and feel… and allow the trees to teach you what words alone cannot hold.
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