Mind Matters News and Analysis on Natural and Artificial Intelligence
old tree roots in a green forest
scenery of two old tree roots in a beautiful green forest

New Research Suggests That Plants Can “Think”

But what does that mean? Clearly not what some people expect

In an interview with Suzanne Simard, a forestry prof at the University of British Columbia, science writer Brandon Keim explores the way mother trees, other trees, and a dense network of fungi in forests stay in constant communication. In many ways, it’s strikingly like animal intelligence.

Keim asked her whether she thought plants had a sense of “self”:

Probably the best evidence we have—and keep in mind that scientists have looked at humans and animals a lot longer than plants—is kin recognition between trees and seedlings that are their own kin. Those old trees can tell which seedlings are of their own seed. We don’t completely understand how they do it, but we know there are very sophisticated actions going on between fungi associated with those particular trees. We know these old trees are changing their behavior in ways that give advantages to their own kin. Then the kin responds in sophisticated ways by growing better or having better chemistry. A parent tree will even kill off its own offspring if they’re not in a good place to grow.

Brandon Keim, “Never Underestimate the Intelligence of Trees” at Nautilus

That’s more than we expected to learn about trees. But, assuming the research is replicated, it doesn’t quite add up to a sense of self. Recognizing chemical signals (or not), without any conscious awareness, would suffice.

Keim went on to ask, “Can a mother tree choose whether or not to provide care, and then at some level does she know this?”:

We have done what we call choice experiments, in which we have a mother tree, a kin seedling, and a stranger seedling. The mother tree can choose which one to provide for. We found that she’ll provide for her own kin over something that’s not her kin. Another experiment is where a mother tree is ill and providing resources for strangers versus kin. There’s differentiation there, too. As she’s ill and dying, she provides more for her kin.

We’ve done lots of experiments where we adjust the health of the donor—the mother tree—versus the health of the recipient, the seedling, by altering levels of shade or nitrogen or water. It matters what condition each of them is in; they can perceive each other, and those decisions are made depending on conditions. If we suppress the health of the recipient seedling, the mother tree will provide more resources than if we don’t.

Brandon Keim, “Never Underestimate the Intelligence of Trees” at Nautilus

Again, research suggests that the world of trees is vastly more complex than we have supposed and Simard is right to see that we neglect it at our peril. But she does not demonstrate that the tree is doing any thinking. Pest insects and deadly bacteria can communicate and change their environment (often the environment is the human body) just as well as plants. But we are less apt to endow them with romantic qualities.

A philosopher like Steve Meyer would say that there is an intelligence beyond nature which did a lot of thinking to make all these complex interactions possible. But that intelligence, assuming you accept its existence, does not reside in the tree or insect.

A recent discovery showed that plants use glutamate neurotransmitters, as mammals do, to shape their environment, emit clouds of warning chemicals, etc. However, the further claims we now hear that plants are conscious or have a sense of purpose, etc., are a product of the human imagination. They are reminiscent of claims decades ago that dolphins speak a human-like language, “Dolphinese.” The program did not provide much insight and was harmful to the dolphins.

From time immemorial, we have endowed what we find in nature with our own characteristics. That is called mythology. The people who think that salad is murder or beg plants to forgive their sins are not helping the environment; they are incorporating a mythology into their lives:

Union Theological Seminary (UTS), a progressive-identifying school located in New York City, which is affiliated with nearby Columbia University, tweeted out a picture and message on Tuesday from a chapel meeting where students gathered around various plants as an “offering” to the “beings who sustain us but whose gift we too often fail to honor.” The tweet asked the question, “What do you confess to the plants in your life?”

In subsequent tweets following the initial announcement, the school continued to refer to plants as “beings,” and acknowledged they were “worshiping,” and “speaking directly in repentance.”

Michael Marcavage, “Seminary Students Repent to Plants, ‘Confess’ and ‘Sorrow in Prayer’ to Vegetation in Chapel Ceremony” at Christian News

“Forgive me, Gourd, for I have sinned?” Any relationship between this nonsense and science or stewardship of our environment is, alas, incidental.

What we are learning today is that the ability to exchange information is very widespread among life forms but rational thought is unique to humans. So a fellow human might “forgive” the Union seminarians for forgetting to water the garden; the garden can’t. But decades of accepted claims that the human mind is simply an accidentally overdeveloped animal mind has robbed many of the ability to make such common-sense distinctions.


Further reading on plant communications: Scientists: Plants Are NOT Conscious! No, but why do serious plant scientists even need to make that clear? What has happened? Quite simply, the need to see humans as equivalent to animals has now spread to the need to see us as equivalent to plants.

Can plants be as smart as animals? Seeking to thrive and grow, plants communicate extensively, without a mind or a brain

Is salad murder? If we think plants are “equal organisms” with respect to humans, it’s not clear whether salad is or isn’t murder. Or whether murder is even a serious ethical problem.

Researchers: Yes, plants have nervous systems too. Not only that but, like mammals, they use glutamate to speed transmission


Denyse O'Leary

Denyse O'Leary is a freelance journalist based in Ottawa, Canada. Specializing in faith and science issues, she has published two books on the topic: Faith@Science and By Design or by Chance? She has written for publications such as The Toronto Star, The Globe & Mail, and Canadian Living. She is co-author, with neuroscientist Mario Beauregard, of The Spiritual Brain: A Neuroscientist'€™s Case for the Existence of the Soul. She received her degree in honors English language and literature.

New Research Suggests That Plants Can “Think”