# How Science Changes Its Mind (About Plants) ## How Science Changes Its Mind (About Plants) Thinking with Plants and Fungi Conference 2025 Zoë Schlanger, Writer and Author of *The Light Eaters* ![](/sites/g/files/omnuum4346/files/styles/hwp_21_9__1920x825/public/2026-01/LightGreen1-01.png?itok=qM5slz26) *This chapter was adapted from remarks given by Zoë Schlanger’s at the Thinking with Plants and Fungi Conference organized by the Center for the Study of World Religions in May 2025.* --- I’m a climate journalist, and I primarily cover two things: climate change and air and water pollution. That means I’m covering the willful destruction of our planet. It’s incredibly bleak stuff. Several years ago, I felt myself burning out on that material and went looking for something that felt more like a form of flourishing than a form of dying. I quickly found plants. But more importantly, I found botanists whose enthusiasm for plants was incredibly infectious. And I realized these were the only people I wanted to talk to for a while. I also realized I had stumbled upon the field at a very exciting time. Emerging research was finding remarkable capabilities in plants to do things like respond to acoustic vibrations, behave differently toward their kin than toward stranger plants of the same species, respond to touch, do simple math, and manipulate predators. These advancements felt like pieces of a much bigger story. But science can be fragmentary, and new information accretes slowly through a thousand small discoveries, which can make the bigger picture impossible to see. I wanted to unite all these little pieces and understand what all this could possibly mean. The result was my book *The Light Eaters*, which traces the history and future of the field of plant-behavior research and asks where, if anywhere, plant intelligence—or even consciousness—might be found. In reporting the book, one of my earliest calls was to Elizabeth van Volkenburgh, an accomplished plant physiologist, professor emerita at the University of Washington Seattle, and the president of a group called the Society of Plant Signaling and Behavior, formerly known as the Society for Plant Neurobiology. I wanted to hear about this moment in botany from her. That call began a fascinating, years-long conversation with Liz, who recounts her own journey in the chapter included in this volume. I began to understand the tremendous controversy I had stumbled into. The broad strokes: On the one hand, plant scientists were arguing it was time to expand the definition of intelligence to include plants, which were clearly making spontaneous decisions. Isn’t the ability to make a wise decision a hallmark of intelligence? Plus, they said, this rhetorical shift could spark more serious inquiry into plant behavior and accelerate discovery in that field. And then there was the other side—plant scientists who were calling all this ridiculous. Plenty of good science had been published by folks in the plant-intelligence camp, the skeptics conceded. But their proposal cheapened plants, they said, by using anthropocentric or zoocentric terms for them. By comparing plants to ourselves, we make ourselves the standard. Instead, skeptics argued, we ought to allow plants to be their own standard, to give intellectual space to the fact that plants diverged from our own branch of life so long ago that evolution equipped them with an entirely different way of being alive. That remove—approaching plants on their own terms, not on ours—would account for the true depth of their otherness and the many skills they have that we don’t. That means not using words like *neurobiology* or *intelligence* when discussing them. I find this argument reasonable, but something about the entire debate fell short for me. Fighting over language didn’t change the remarkable things that scientists were learning. Perhaps *agency* is a less contentious word to use. If agency is the quality of having a stake in the future of one’s life, being an active participant in one’s survival, plants, we now know, clearly have that. Whatever the verbiage, the old image of plants as passive had clearly run its course. It was time for something new. But to start, let’s go back to the 1970s, when a zoologist named David Rhoades noticed something strange happening in a forest south of the University of Washington, where he studied insects. A blight of web-forming caterpillars was defoliating the alders and willows in the area. A tree without leaves cannot “eat” light; it effectively starves to death. But then the tides suddenly turned. The caterpillars started dying and the trees were bouncing back. What had happened to the caterpillars? Rhoades knew what all ecologists know, which is that in an ecosystem everything happens for a reason—nothing is pure chance. The reason in this case was that the willows and alders had changed the chemistry of their leaves to become less nutritious. Now the *caterpillars* were starving. ![California Sagebrush](/sites/g/files/omnuum4346/files/styles/hwp_1_1__360x360_scale/public/2026-01/Screenshot%202026-01-21%20123019.png?itok=ixdGDM6B) *California sagebrush (Artemisia californica).* Photo by Dana L. Brown.But what was more surprising was that some trees had changed their leaves before the caterpillars had even reached them, as if they’d received advance warning. A shocking possibility presented itself: The trees must be signaling to one another. Rhoades published this paper in an obscure volume in 1983, suggesting that trees used “airborne pheromonal substances” to communicate.[1](#references) This paper would ultimately change everything about botany, but in a cruel twist, it would end his career, because in that moment no one believed him. Fast forward to now, more than forty years hence, and communication between plants is a known—and mostly accepted, although still debated—phenomenon. Plants are indeed geniuses at biosynthesis. Their capacity to build and deploy complex chemical compounds that drift on the air or seep through the soil and carry meaning that can be interpreted by other organisms is an entirely additional sense, one we hardly have at all. Yet Rhoades died believing his work was incorrect. In response to criticism levied at the time, he tried to replicate his findings, but his original research had been done in the spring and he tried to replicate it in the fall, and what he didn’t know then is that chemical signaling is one of the many seasonal changes a plant goes through. It wasn’t that he was wrong; there were just more variables hidden from his view. Science is a conservative institution, with good reason. Researchers understand the tremendous responsibility of their position. They want to be sure that a big new idea is supportable and replicable before they sign on. They know they are a backstop against false information creeping in and tainting any work built on top of it. And that profound skepticism can mean it takes a long time for new ideas to gain traction. Counterintuitively, scientists themselves also tend to resist scientific discovery, which is itself a known and studied phenomenon. Rhoades’s story reminds us that at any moment science is a snapshot of what a particular discipline believes. It can and does change its mind—sometimes dramatically—and it was clear to me when I began reporting for my book that botany was in an era of changing its mind about plants as a whole. So I quit my job and changed my life. I decided to think about plants full time. I began traveling to meet botanists. I went to California to see Richard Karban at UC Davis and meet the plot of sagebrush bushes he’s been tending for 20 years. He knows each of their chemical profiles quite intimately. He has witnessed plenty of chemical communication between them, communication that differs between genetic kin and stranger plants. And he’s also found that his sagebrush seems to take on regional dialects of a more universal chemical language, so to speak, when they’re geographically isolated. Karban, in many ways, is extending Rhoades’s earlier work. ![Puyehue plant with small white berries](/sites/g/files/omnuum4346/files/styles/hwp_1_1__360x360_scale/public/2026-01/Screenshot%202026-01-21%20114810.png?itok=cPBTay4-) **Boquila trifoliolata** in *Parque Nacional Puyehue*, Chile. Photo by *tonyrebelo*,I also went to the University of Wisconsin–Madison, to the lab of Simon Gilroy, to pinch his mutant plants with tweezers. These plants had been suffused with a jellyfish protein that gave them to capacity to glow. The tweezers were dipped in glutamate, a neurotransmitter in our own bodies, which appeared to boost signals of touch in plants. When we pinched the midrib of a leaf under a microscope, we watched a green light emanate through the plant, rippling from the wound site outward. The glow was a proxy for how the plants were responding to touch in real time; the signal of my pinch moved across the entire plant within two minutes. Simon and I spoke a lot about what his findings meant. Plants clearly have a means of altering their whole body in response to a touch or a wound suffered only in one part, despite, of course, not having a brain. The signaling system appears to involve neurotransmitters, and possibly “action potentials,” or electricity. But plants have no neurons or synapses. Still, that didn’t stop two molecular biologists from writing in *Science* that Gilroy had found “nervous system-like signaling” in plants. A neuroscientist, writing in another journal, drew parallels to animal nervous systems too. I went to a temperate rainforest in southern Chile, in Puyehue National Park, to meet Ernesto Gianoli. Ernesto spent two decades teaching and researching at Chilean universities and is now a professor at Tarleton State University in Stephenville, Texas. His work on the ecology of plants focuses on their plasticity, meaning the range of body plans and traits they can express under various environmental conditions. In 2014 he discovered an incredible fact about a very ordinary-looking vine. You may have heard of the “chameleon vine,” *Boquila trifoliolata*. Ernesto discovered that *Boquila* can mimic virtually any plant it grows beside. It is the first plant known to be capable of this truly spontaneous version of mimicry. It can change its leaf shape, vein pattern, texture, and color to match or approximate almost anything it’s growing beside—or at least it tries. I had the privilege of finding the first case of *Boquila* mimicking a fern, which is a testament to the paucity of research on this plant in its natural environment: It’s really just Ernesto out there looking at *Boquila* in the wild. Every time he goes down to Puyehue National Park, he tells me he finds new versions of its mimicry, adding to the list of what it can do. Ernesto also showed me a case of a *Boquila* mimicking a bush called *Rhaphithamnus spinosus*, a plant with glossy, dark green little leaves that each grow a hard spike at their tip that curls under the leaf like a hook. Ernesto explained that a spike on a leaf tip tends to be a defining attribute of species that have them, but when he told me to drag my finger beneath the leaf of a nearby mimicking *Boquila*, I found it had grown a curled spike too. He said this would be the equivalent of a human growing a rhinoceros tusk—it just doesn’t happen. *Boquila* sometimes tries and fails to imitate species. For example, we saw a particular type of *Ranunculus* with lacy leaves, and a baby *Boquila* plant trying its best to modify its own leaves to match. Instead, it just looked lumpy. But remarkably, that *Ranunculus* had been introduced to the forest within the last 20 years. This tells us that even if it is not always particularly impressive, *Boquila*’s mimicry is indeed spontaneous, rather than reliant on long evolutionary relationships. The mechanism for this mimicry is still unknown. Ernesto’s discovery, much to his chagrin, has provoked a debate about whether it can be said that plants have some kind of ability to see. Some argue that *Boquila* must be interpreting visual information about its neighbors, because contact is unnecessary for the mimicry to be activated. A few researchers in Europe are trying to prove this theory now. But Ernesto has a different theory which suggests some kind of microbial invasion may be responsible for the mimicry, an idea even more sci-fi and alluring to me than the vision hypothesis. This displaces any notion of “intelligence” beyond the plant itself, and on to a collection of multitudinous individuals. Categories falter. Composite organisms come into view, complicating everything delightfully. My role as a science journalist is not really to adjudicate debates like this. It’s to chart a path through the science for a lay reader. The current profusion of exciting and rigorous plant research has the potential to upend our understanding of these organisms, and as a lay reader myself I think the public ought to hear more about it. The entire debate makes me think of many points in history where science has dramatically changed its mind. One of them was the era of vivisection—how, until the end of the 19th century, medicine was taught in part by performing live surgery demonstrations on unanesthetized dogs. It was thought that only humans could experience sensations like pain. That was the scientific consensus at the time. Vivisection did not ultimately end because science changed its mind on that count—though eventually, of course, it did. It ended because a group of animal welfare activists made it socially unacceptable to continue doing it. It changed because of a social shift, not necessarily a scientific one. This reminds me that science is constrained by the questions scientists are trained to consider “scientific” enough to ask. Research is opening doors in plant science to new types of questions that shatter prior assumptions about what plants are and what they’re capable of. The discoveries being made now highlight the fact that plants are anything but passive; they take an active part in their lives. They sense their world. They respond in kind. And these findings settle us back into our place in the world, which is a profoundly humble place. They remind us that we are not the pinnacle of the evolutionary tree or the top of a ladder. Evolution, after all, is not linear. It’s not hierarchical. We are each nodes on an entangled web—just one example of an endlessly unfurling project of biological creativity. Perhaps ours is not the only way to be clever. Certainly, our way of doing things is not the only way to be creatures with an active stake in the direction of their lives, a talent for planning their futures, or the ability to make wise choices in an endlessly shifting world. I’m going to close with a thought borrowed from the science historian Thomas Kuhn. He wrote that after a scientific paradigm shift, it is “as if the professional community had been suddenly transported to another planet.” The familiar, seen through a new lens, looks suddenly alien. These moments have the power to radically change one’s view of the world in which we live. But of course, as Kuhn himself reminds us, the world itself stays the same. In the end, plants will go on being plants, whatever we decide to think of them. I think the questions of intelligence or consciousness or agency in plants are not science questions at all. Rather, they’re questions about how we assign meaning to what science observes. In many ways they belong to the realm of humanities, to ethics, and philosophy. Zoë Schlanger ### Author Biography Zoë Schlanger is a staff writer at *The Atlantic*, where she covers climate change. She is the author of *The Light Eaters* (HarperCollins, 2024), a New York Times bestselling book about the world of plant behavior and intelligence research. Her work has appeared in *The New York Times*, *The New York Review of Books*, and on NPR, among other major outlets. She was the recipient of a 2017 National Association of Science Writers reporting award for coverage of air pollution in Detroit and a finalist for the 2019 Livingston Award for a series on water politics at the Texas-Mexico border. She lives in New York. ![Zoe Schlanger headshot](/sites/g/files/omnuum4346/files/styles/hwp_1_1__480x480/public/2024-11/YaelMalka_ZoeSchlanger_Portraits_17789%201.jpg?itok=rBFC_5IQ) ### Footnotes 1 David F. Rhoades, “Responses of Alder and Willow to Attack by Tent Caterpillars and Webworms: Evidence for Pheromonal Sensitivity of Willows,” ACS Symposium Series 208, January 20, 1983. [\[Return to Section\]](#section2) #### Suggested Citation Schlanger, *Zoë*. "How Science Changes Its Mind (About Plants)" in *Thinking with Plants and Fungi: Interdisciplinary Explorations of Ecology, Mind, and the More-than-Human World*, edited by Rachael Petersen, Russell Powell, and Natalia Scott Schwein. Center for the Study of World Religions, Harvard Divinity School, 2026.