Never underestimate the intelligence of trees

Consider a forest: One notices the trunks, of course, and the canopy. If a few roots project artfully above the soil and fallen leaves, one notices those too, but with little thought for a matrix that may spread as deep and wide as the branches above. Fungi don’t register at all except for a sprinkling of mushrooms; those are regarded in isolation, rather than as the fruiting tips of a vast underground lattice intertwined with those roots. The world beneath the earth is as rich as the one above.

For the past two decades, Suzanne Simard, a professor in the Department of Forest & Conservation at the University of British Columbia, has studied that unappreciated underworld. Her specialty is mycorrhizae: the symbiotic unions of fungi and root long known to help plants absorb nutrients from soil. Beginning with landmark experiments describing how carbon flowed between paper birch and Douglas fir trees, Simard found that mycorrhizae didn’t just connect trees to the earth, but to each other as well.

Simard went on to show how mycorrhizae-linked trees form networks, with individuals she dubbed Mother Trees at the center of communities that are in turn linked to one another, exchanging nutrients and water in a literally pulsing web that includes not only trees but all of a forest’s life. These insights had profound implications for our understanding of forest ecology – but that was just the start.

It’s not just nutrient flows that Simard describes. It’s communication. She – and other scientists studying roots, and also chemical signals and even the sounds plants make – have pushed the study of plants into the realm of intelligence. Rather than biological automata, they might be understood as creatures with capacities that in animals are readily regarded as learning, memory, decision-making, and even agency.

This can be difficult to wrap one’s head around. Plants are not supposed to be smart, at least not according to the rubric of traditions known as western thought. There’s also a case to be made that, while these behaviours are indeed extraordinary, they don’t map neatly onto what people usually mean by learning and memory and communication. Perhaps trying to define plants’ behaviour according to our own narrow conceptions risks obscuring what is unique about their intelligence.

It’s a rich and fascinating debate, one that won’t be answered without a great deal more research – and that research ought to be conducted with an open mind to the possibility that plants have minds. Simard spoke with Nautilus from her office at the University of British Columbia about the horizons of her work.

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