Back when I only visited the countryside occasionally, I suffered from what botanists call “plant blindness,” described by Zoë Schlanger in her entertaining new book, The Light Eaters, as “the tendency to view plant life as an indistinguishable mass, a green smudge, rather than as thousands of genetically separate and fragile individuals, as distinct from one another as a lion is from a trout.” Now that I live in small-town New England, I’m a bit more literate in the flora I see. A stand of Japanese knotweed, the bamboo-like invasive I’m constantly beating back to the margins of my own yard, indicates there must be a brook or other waterway out there, since that’s how the plant spreads. One wild apple tree by the roadside may have sprouted from a core tossed out of a car, but two or more suggests an old farmstead now consumed by the surrounding brush. I now know I will pine in vain forever for my own patch of partridge berry, a ground cover that flourishes along my favorite trail because it obviously prefers growing in pine needles instead of under the deciduous trees in my yard. But above all, I know that a lifetime of study couldn’t tell me everything that’s going on out there in the green. And the thrill I get every time a seed I’ve planted germinates never dims.
The vegetable kingdom is full of wonders and mysteries, as Schlanger lavishly demonstrates in The Light Eaters. For one, plants created Earth’s atmosphere, oxygenating it and making it breathable for animals like us. Likewise, she explains, “every thought that has ever passed through your brain was made possible by plants,” because every animal organ is made out of sugars produced by photosynthesis, the wizardry through which plants transform light and air into the fuel that built and powers our bodies.
Yet are we grateful? We take plants for granted and seldom spend much of the brainpower they supply on considering their multiplicity and unsung abilities. When it comes to plant blindness, though, Schlanger may be overstating her case, given that somewhere between 55 and 80 percent of Americans participate in some form of gardening. (Admittedly, that’s according to surveys conducted by various players in the gardening industry, but doesn’t everyone know at least one fanatical gardener? I have a friend who accuses me of paying more attention to the fruit tree saplings I’ve planted than to my actual family.) Nevertheless, Schlanger is probably right in thinking that most modern humans regard plants as alive but not animate—a bit boring by the standards of creatures that can move around freely.
By Zoë Schlanger. Harper.
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What few of us know about, and what Schlanger makes the focus of The Light Eaters, is the controversy raging among botanists about plant behavior—and even about using the word “behavior” with regard to plants—resulting in career-scuttling opprobrium and professional taboos. Forget the Necronomicon, that dread tome from the fiction of H.P. Lovecraft. If ever there was a cursed book it’s Peter Tompkins and Christopher Bird’s 1973 bestseller, The Secret Life of Plants, which convinced people that their houseplants enjoyed being talked to and preferred listening to classical music over rock. While Schlanger describes the book as “a beautiful collection of myths,” the irresponsible and unsubstantiated claims it made tainted the entire field of plant behavior research. Botanists told Schlanger that in the years following The Secret Life of Plants, “the National Science Foundation became more reluctant to give grants to anyone studying plants’ responses to their environment.”
Photo by Heather Sten
Only in the recent past has this cloud passed from the face of botany, allowing researchers to celebrate such wonders as a Chilean vine that conceals itself from herbivores by mimicking the leaves of nearby plants of entirely different species. Plant-friendly readers have probably already learned (from such popular books as Peter Wohlleben’s The Hidden Life of Trees) that roots have symbiotic relationships with fungi in the soil, allowing them to connect to other roots to transmit information to and from their neighbors. Plants, as the scientists Schlanger interviews have learned, can also respond to assaults from, say, leaf-munching caterpillars by changing their own chemical composition to repel or even poison the attackers. They can then pump scents into the air to warn other plants to armor up as well or to attract predators who feed on the pests. Some of them can even tell whether a nearby plant of the same species is a close genetic relative and moderate their competition for nutrients accordingly. “The more botanists uncovered the complexity of forms and behaviors of plants,” Schlanger writes of these changing views, “the less the traditional assumptions about plant life seemed to apply.”
The Light Eaters is one of those science books in which the author travels to richly described locales to interview assorted researchers at work and to vividly describe their discoveries for a general audience. (Ed Yong’s An Immense World, about the sensory universe of animals, is the best-known recent example.) In addition to identifying that Chilean vine firsthand, Schlanger hikes through Pacific Northwest rainforests, strolls through gingko-tree groves in Virginia, visits sagebrush fields in California, and drops in on the 1800s Scottish farmhouse where an 83-year-old pioneer in the study of plant behavior grumpily acknowledges his belief “that plants are probably intelligent, and that intelligence is probably a property of all living things.”
This assertion is something of a holy grail for Schlanger, who spends much of the book seeking confirmation from her scientist subjects that plants could be “intelligent” and perhaps even possess “consciousness.” The fact that there isn’t a scientific consensus on how to define either of those terms makes it especially difficult to pin them to an edge case like plants, which don’t have brains or nervous systems. Plants do exhibit behavior, of a sort—they react to their environments, and some even seem to retain “memories” of, say, the time of day when pollinators visit. But without a clear understanding of what it means to be intelligent or conscious, it’s hard to say if this qualifies as either. For herself, Schlanger decides that intelligence means “the ability to learn from one’s surroundings and make decisions that best support one’s life,” and that plants meet this criterion.
This quest, while it provides a narrative thread for the book, becomes the one thorn among the otherwise lush pleasures of The Light Eaters. Why is it so important to Schlanger that plants be acknowledged as “intelligent” by these humans? In addition, she often seeks out evidence that plants exhibit a set of qualities prized by the woozy, vaguely liberal sentimentalism that’s common in popular nature books. (I’m looking at you, The Hidden Life of Trees.) Plants aren’t just individual monads competing in a ruthless Darwinian struggle to survive, she observes—they cooperate and help each other. Plants challenge the line drawn between the “spiritual and scientific worlds.” Plant sexuality “gleefully defies heteronormative modes of reproduction.” Plants demonstrate that nurture matters just as much as nature, debunking the “all-or-nothing thinking to which Western science tends to be devoted.”
The reasons for this very common way of framing nature writing are obvious. Human beings (a group to which—whatever the formidable abilities of plants—every potential reader belongs) can’t resist drawing parallels between themselves and other creatures. We are forever searching for “lessons” about how to conduct ourselves from the behavior of living things with whom we often don’t have much in common. There’s a long history of justifying various human actions by referring to dubious beliefs about how “nature” works. Proving that plants cooperate with each other becomes an argument for why people should as well. Schlanger writes that we ought to pay attention to the “social, collective intelligence” of plants because “we may be missing a big part of the story of our own existence without it.”
Nevertheless, in the final chapter of The Light Eaters, Schlanger suddenly, briefly rolls all this back. Rejecting the anthropomorphism that permeates the preceding 10 chapters, she cautions that “putting too human a sheen on plant intelligence is a failure of imagination.” Indeed. As enjoyable as The Light Eaters is, this failure does limit it. Where Yong made An Immense World more wondrous by emphasizing the dissimilarities between human and animal perception, until that final chapter Schlanger seems to insist that if we can’t identify with plants and see forms of our own experience in their very alien way of being, we will continue to disrespect and ignore them.
But one of the things we love most in plants is the enormous difference between them and us. The human looking to decompress from a rough day at the office certainly doesn’t take a walk in the woods because trees are like people. The strangeness of plants; their (apparent) stillness and slowness; their resilience; their ability to survive on air, water, and dirt; their capacity to transform garbage into food and desolation into beauty, all in the course of pursuing their own unfathomable business: These are the unsung miracles that surround us daily. At its best, The Light Eaters ushers those marvels onto center stage. These characteristics don’t need to be the result of “intelligence”—whatever that is—or any other trait or behavior or idea we’d like to see more of in our human compatriots. They may well be the product of forces so profoundly other that we’ll never entirely understand them, although it’s exciting to try. A window is always better than a mirror.
