As a boy I used to fall asleep at night listening to a cassette tape of Shel Silverstein reading Where the Sidewalk Ends. Silverstein’s voice, accentuated by the cassette player’s tinny speakers and whispering gears, was high and slightly rough, but playful and welcoming, a gravel country road kind of voice. My favorite tracks at the time were the ones that displayed Silverstein’s bizarre sense of humor: the sharp-toothed snail inside your nose ready to bite off your finger, the sadistic dentist pulling the teeth of a crocodile, the silly king’s jaws stuck together with an “extra sticky peanut butter sandwich.” I didn’t think much of the plaintive “Forgotten Language,” in which Silverstein, accompanied by a few acoustic guitar chords and a synthesizer emulating the descent of a “falling, dying flake of snow,” recalls:

Once, I spoke the language of the flowers.
How did it go?
How did it go?

Silverstein’s poem was lost on me in part because children are not often nostalgic for childhood. But also: I was living it. I loved plants. Like many of my friends I spent time at Nola Brantley Memorial Library, but I checked out as many books from the adult nonfiction shelves as I did from the children’s section – titles like Mel Bartholomew’s Square Foot Gardening, or Jerry Baker’s Flowering Garden. I joined a seed exchange I’d discovered in a magazine that, for reasons mysterious to me, was called Reminisce, and gained some elderly lady pen pals as a result. At one point in middle school, my garden portfolio included a vegetable garden; an herb garden; a sunny perennial border with chrysanthemums and false indigo; a shade garden with ferns and hostas; and – thanks to the herculean efforts of my slightly reluctant father in the red-clay subsoil of our backyard – a water garden: a tiny pond with orange and white shubunkin fish, a trickling waterfall, waterlilies, yellow irises, and at least one leech. (I was an ambitious but not very knowledgeable collector of aquatic wildlife.) In addition to bloodsucking worms, I also collected cuttings and seeds and other natural ephemera. My mother sewed me a vest with pockets and straps to hold the pill bottles I used for collecting seeds. And I wore it. I was a weird kid.

The language of the flowers – how did it go? That is what I want to know too. It seemed easy enough as a child. It is also, I have recently learned, a common tongue for many humans from many places and times. I was, as a nine- or ten-year-old, a member of that majority, the folks since time out of mind who have assumed that plants could talk.

What is the language of the flowers? At the most literal level, florists have long been keen to sell us on the symbology of certain species and colors. The nineteenth century, with its advances in climate-controlled growing and shipping and its tremendous expansion in rules of etiquette, saw a dramatic increase in the floral trade, and, not surprisingly, a flurry of books purporting to guide consumers on how to speak with flowers. One popular 1855 volume was called Flora’s Lexicon. The subtitle of an 1864 volume on “The Language and Sentiment of Flowers” promised that it contained “the name of every flower to which a sentiment has been assigned.” Such flower guides were essentially code manuals for senders and recipients. According to The Language of Flowers, published by F. Warne, a peach blossom meant “Your qualities, like your charms, are unequalled,” whereas a mignonette meant “Your qualities surpass your charms” and a spindle tree said “Your charms are engraven on my heart.” According to Arthur ­Freeling’s Flowers (1851), a bouquet with peach blossoms, box, cypress, marigold, carnation, and lily of the valley meant: “I am your Captive, but your Stoicism drives me to Despair; give me your Love, and return me to Happiness.”

It’s hard to imagine a more anxiety-inducing way to appreciate the botanical world.

People have studied the language of plants for a variety of other reasons, but the most important may be simply that plants are medicine. According to a famous Cherokee origin story, a council of animals, chaired by the grubworm, was called to deal with the problem of human cruelty and injustice toward other animals. After unanimously condemning humans as guilty, the assembly held a session at which they devised the idea of disease as a just revenge. The members of the council named diseases “one after another,” with the grubworm hailing “each new malady with delight” and finally falling over backward in a fit of vengeful joy. (This is why, the narrator informs us, grubworms have crawled on their backs ever since.) The animals were plotting nothing less than extermination.

But then plants, hearing of the animal conspiracy, made haste to help the humans:

Each tree, shrub, and herb, down even to the grasses and mosses, agreed to furnish a remedy for some one of the diseases named, and each said: “I shall appear to help man when he calls upon me in his need.” Thus did medicine originate, and the plants, every one of which has its use if we only knew it, furnish the antidote to counteract the evil wrought by the revengeful animals.… When the doctor is in doubt what treatment to apply for the relief of a patient, the spirit of the plant suggests to him the proper remedy.

This origin story, collected in the late nineteenth century by ethnologist James L. Mooney, has much to recommend it, and not just the fact that a grubworm chairs the meeting and falls on his back laughing maniacally. Modern epidemiology has confirmed that diseases do in fact jump from animals to humans. Bubonic plague, Lyme disease, malaria, sleeping sickness, E. coli, salmonella, swine flu, bird flu, and perhaps Covid-19 have animal vectors. Most of the “virgin soil” epidemic diseases faced by indigenous people at the time of contact exploited the lack of livestock-keeping among Native Americans, which had left their immune systems vulnerable to European pathogens. One wonders if the grubworm story pays a sort of homage to this devastating fact.

Even more intriguingly, the Cherokee story portrays plants not just as useful materials but as active agents of healing. The spirit of the plant suggests the proper remedy. Every plant would furnish an antidote, if we only knew it. In early modern Europe, the general assumption that plants were divinely ordained as cures was systematized as the “doctrine of signatures,” the idea that plants were often marked or signed to indicate their purpose. Ferns, with their fiddleheads stretching out into healthy fronds, for arthritis and rheumatism. An orchid shaped like male genitalia for impotence. Saxifrage, which appears to break apart the rocks it grows upon, for kidney stones. Eyebright, with its striped petals resembling bloodshot eyes, for ocular problems. Signatures may also be related to place: the willow tree, growing in the same sort of low, wet ground thought to produce chills and fever, seemed a good treatment for the same – and actually was, since willow bark contains salicylic acid, the active agent in aspirin. Sassafras and guaiacum, New World plants with strong aromas, seemed likely to cure syphilis, also thought to originate in the New World.

This notion that plants would be “signed” with their uses is appealing, for obvious reasons. Human health is complex and mysterious, and it’s nice to think that we haven’t been abandoned to our deaths. Salicylic acid from willow bark might be the most famous success of this approach to medicinal plants, but it also seems that purslane’s reddish fleshy stalks, which look a little like worms, are somewhat effective in “controlling intestinal parasite loads,” and that eyebright drops actually can be used to treat conjunctivitis. And smell and taste have long served as signs of potential uses and dangers. Spices like garlic, allspice, oregano, cloves, and capsicums or hot peppers, as biologists Paul W. Sherman and Jennifer Billing have documented, seem generally to have antibacterial properties. Among the Matsigenka and Yora societies in the Amazon, bitter or even poisonous plants were thought to drive out disease, while aromatic infusions kept “malodorous spirits and illness-causing vapors at bay.” As the ethnobotanist Bradley C. Bennett has argued, it’s probably best to see signatures not as a way to find cures but as a kind of mnemonic for dissemination of useful knowledge, created after a plant was discovered to be useful – a way to capture what had already been learned through careful study and experimentation.

Traditional knowledge has often served as a guide for modern pharmacology. The common landscape annual rosy periwinkle (Catharanthus roseus) had a wide range of traditional uses across Indian Ocean societies before it became an anti-cancer wonder drug in the twentieth century. And as Gabriela Soto Laveaga documents in Jungle Laboratories, modern birth control pills depended in part on the ecological knowledge and labor of thousands of Mexican campesinos who harvested the wild yam called barbasco containing a component of artificial progesterone. Western science has often behaved like a buyer bargaining for a deal, disparaging the good they ultimately resell for a hefty profit. It’s all superstitious nonsense – until there’s a valuable chemical component at stake.

But the inverse of this dynamic is just as problematic – a kind of credulous acceptance of traditional knowledge as good by definition. It is certainly comforting to think that “food is medicine,” that an avocado’s uterus-like shape signifies an ability to prevent birth defects, or that a fig’s resemblance to a testicle indicates its effectiveness for increasing sperm motility (as blithely indicated by one YouTuber with more than a million followers). But plants can be powerful for good or for ill, and the doctrine of signatures can be facile and therefore dangerous. To cite just one well-known example: the flowers of birthwort (Aristolochia clematitis) bear some resemblance to a uterus and the plant was used to induce both menstruation and childbirth (aristolochia derives from the Greek for “better birthing”), but the active ingredient aristolochic acid is a proven toxin that results in fatal kidney failure.

Renaissance advocates of the doctrine of signatures also had some very bad ideas. Theophrastus Bombastus von Hohenheim, more commonly known as Paracelsus, not only had the distinction of having “bombast” for a middle name but was a noted alchemist and physiognomist. In Concerning the Nature of Things he pronounced unequivocal judgments of people’s characters based on their facial features: a flat nose, for instance, indicated “a malignant man, false, lustful, untruthful, inconstant.” Meanwhile, Giambattista della Porta’s twenty-book magnum opus, appropriately titled Natural Magick, presented a dizzying array of the esoteric, the experimental, and the practical. His instructions on how to “make great lettuce” – dig around its roots and add ox dung and water – were reasonable enough. But he also thought that wasps generated from horse carcasses, and serpents from the hair of a menstruating woman. In the section on “Beautifying Women,” his advice on how to “correct the ill scent of the armpits” was to smear them with artichoke roots.

So no, as appealing as artichoke roots in the armpits might be, I’m not recommending a return to the doctrine of signatures. It’s not the medicine itself that is most intriguing, nor even the way people supposedly discovered them by careful observation. It is a bit too comfortable to imply that advocates of the doctrine of signatures were just good observers of the natural world, protoscientists practicing a protoscientific method. They thought something far more mysterious and powerful was going on, that they were tapping into a vital substance running underneath the surface of all life. In their work, the line between the spiritual and the physical is hard to trace.

But I do think we can recover something of their intensity of focus, as well as the old assumption that the world is full of hidden potency. We might discover and behold with them the significance and integrity of other beings – not least the plants that grow all around us.

At one level, it is a daily absurdity how unaware of plants most of us are. I am wearing cotton jeans, writing on a page made of pine pulp and staring at a screen reinforced with wood fibers, sitting on a rock maple chair at an oak table, fueled by a breakfast of wheat and broccoli and peppercorns, and breathing air that depends on plants reliably playing their part in the oxygen cycle. A recent biomass study estimates that the earth’s plants collectively weigh about 450 gigatons, or more than 80 percent of total biomass. Humans are a tiny fraction, a mere 0.06 gigatons. And yet for many of us plants are little more than scenery on the one hand and resources on the other. This is what biology educators sometimes call “plant blindness” or “plant-awareness disparity”: a failure to see, an assumption of inertness and immobility, an indifference to ecological relationships and biochemical cycles, and an ignorance of form, growth habits, coevolution, reproduction, tactility, and taste.

And yet we do forget, ignore, disdain. There’s a scene toward the end of John Steinbeck’s East of Eden when Adam Trask casually dismisses the meaningless affairs of children, only to be rebuked by his Chinese-American servant Lee. “Do you think the thoughts of people suddenly become important at a given age? Do you have sharper feelings or clearer thoughts now than when you were ten? Do you see as well, hear as well, taste as vitally?” It is “one of the great fallacies,” Lee says, “that time gives much of anything but years and sadness to a man.”

Adults do sometimes recover the sense of wonder, though – often, it seems, by way of sorrow. Solomon Northup, kidnapped into slavery in 1841, found surprising solace in the plantation’s pleasure garden full of pomegranates, oranges, and jasmine vines. A grieving Henry David Thoreau threw himself into natural history observation after his older brother, John, died of lockjaw in 1842. Frances Theodora Parsons’s husband died suddenly of influenza in Europe, and she sailed home to America in January 1891 “exhausted in body and spirit” and drugged with morphine “to insure forgetfulness.” Her family recommended a charitable cause; instead she returned to the woods and meadows she had loved as a child, where she began to study “every flower within reach, noting not only its exquisite and complicated structure but its chosen haunts, its time of blooming and seeding, and even the place it might have held in the minds of poets and of painters.” The result was How to Know the Wildflowers (1893), one of the first natural history guides, which sold out in five days and remained in print for decades. I have a copy my great-grandmother used to identify the wildflowers in the woods around Devon, Pennsylvania. Rudyard Kipling wrote to Parsons of “the debt of pure pleasure that I owe to ‘Wildflowers’ – I have two copies – one very muddy for field use and the other for reading when I can’t go out.”

The list could go on. The poet Michael Longley turned to botanizing in the midst of the Troubles in 1980s Northern Ireland; on the day the ice-cream man on the Lisburn Road was inexplicably murdered he named “the wild flowers of the Burren I had seen in one day: thyme, valerian, loosestrife,” and nineteen others. The beloved British gardener Monty Don, host of the BBC show Gardener’s World, gardens because, he says, it “heals my troubled brain.” In The God of the Garden (2021), singer-songwriter and children’s fantasy author Andrew Peterson describes how trees and gardens pulled him through his own struggles with depression. Jenny Odell’s surprise 2019 bestseller, How to Do Nothing, (and its 2023 follow-up, Saving Time) emerged out of a sense of always-online despair, and she found herself staring at a California buckeye branch several times a week for more than year. Journalist Alexis Madrigal gave up on tech writing – and rediscovered the smell of tomato leaves en route to founding the Oakland Garden Club – because, as he puts it, the internet “is mostly bad now.”

Adults do sometimes recover the sense of wonder, though – often, it seems, by way of sorrow. 

These are the kind of folks I’ve begun to affectionately call “Persons Acting Strange around Plants” or PASAPs. An artist sketching sassafras on the Carolina coast. A surveyor making ink from pokeberries. An ecologist counting broomsedge seeds in the dissected gut of a bobwhite quail. PASAPs are very useful to me as a historian trying to understand the historical roles played by plants, since the plants themselves have left few of their own records.

I’ve become a PASAP myself in recent years – or rather, I’ve renewed a PASAP membership that apparently lapsed sometime in my early twenties. I play at shooting plantain flower heads, pick goldenrod racemes, climb Persian silk trees, and fill my shirttails with dozens of tender figs growing, preposterously, by the vape shop. Plants do their planty things entirely apart from me, and yet they are endearingly accessible at the same time. They seem immune to self-doubt, unfazed by failure, and inexhaustibly purposeful.

I’m convinced we all need PASAPs and other such weirdos in our lives, those who possess what W. H. Auden once called “that eye-on-the-object look.” That look is part of a child’s ordinary cognitive development. Observe a baby fixated on a piece of gum stuck to the sidewalk, or a toddler collecting bits of gravel on every evening stroll, or a preschooler studying an ant mound at the playground. As an adult, I’ve found myself encountering the world as “a disenchanted set of defeated and exhausted objects,” as philosopher Jane Bennett puts it. It’s easy to despair knowledgeably about such a world, and hard to delight in it or care for it. And so I’ve begun collecting again, trying to pay attention, remembering, however falteringly, that there’s always more going on than I can perceive. I’m listening for the plants that talk.