Trevor King/Creative Commons

The Most Dangerous Plant in Britain

On giant hogweed, borders, and belonging

IT IS HARD TO HEAR HIM speak beneath the roar of lorries on Orient Way. Every few seconds, a petrol-scented tailwind gusts along the roadside, and all the branches shudder. Twelve of us are clustered together on this rewilded footpath next to the park, waiting for guidance on our volunteer conservation session. We are meant to be planting trees, little whips we’ve carried out in buckets and wheelbarrows, but our leader has stopped to tell us about weeds instead.

“Here is the difference.” Jonny reaches his gloved hand towards a leaf the size of his head. “This one is okay to touch. That’s the native plant. See how its leaves are more rounded?” He points towards a larger specimen, its leaves jutting out into sharp, toothy points. A line of neon spray paint has been daubed across it. “This one . . . just never, ever touch it.” He goes on to describe the phytochemical burns that can be caused by the plant’s sap, burns that can persist for many years after contact with it. A young man in my group winces, then glances at the leaves again as if to cement them in memory.

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Once Jonny shows us the difference between native and giant hogweed, I’m surprised to realize just how much of the latter grows along the footpath. The spray paint, I learn, is to help the plants stand out when the council comes to destroy it with herbicide. No one seems sure when that’ll be. One of the other volunteers, a pensioner in a blue raincoat who attends every session, tells me there is a whole field of giant hogweed growing at a brownfield site nearby. All the hogweed that has seeded along this path, he says, can be attributed to that abandoned plot.

Native originally to Central Asia, giant hogweed has a reputation in Europe and North America as amongst the worst alien invasive species, a weed so vigorous and dangerous that it has been called “the most dangerous plant in Britain.” But like nearly all foreign species now considered problematic, giant hogweed was brought to Western Europe as an ornamental, prized through the nineteenth century for its large, showy umbels of white flowers. Beyond the space of the garden, it is a species that thrives on disturbed and neglected ground: riverbanks, railway sidings, abandoned plots. Our local park had once been a Victorian dump, falling between a swathe of neglected plots from Walthamstow to the Olympic Park in Stratford, land that had only recently been seen as “useful” again. Land on which the giant hogweed, we learned, had long since found a home.

On the first page of one of my favorite books about plants, Richard Mabey describes weeds as those plants that “obstruct our plans, or our tidy maps of the world.” 

On the first page of one of my favorite books about plants, Richard Mabey describes weeds as those plants that “obstruct our plans, or our tidy maps of the world.” This phrasing captures a lot: notice the “our,” which appears in both clauses, or the word “obstruct,” which tells us how we might judge these plants. The last bit—“tidy maps of the world”—has always stood out to me. Because it is on maps that we draw our borders, and it is borders that most plants do not readily recognize. The giant hogweed had jumped the borders of the nearby wasteland and was crowding into the growth along an increasingly busy footpath. A few specimens had made their way over to Hackney Marshes, where over the summer locals dipped along the banks of the River Lea. Dispersed by wind and water, the seeds had made their way from a site of neglect and disuse into territory that—in the wake of Olympic investment—had only recently begun to be swallowed up by property investors.

Admittedly, I’ve never been that worried by the idea of weeds, perhaps owing to a childhood in a Canadian suburb where herbicide was habitually applied to lawns. At certain times of year, little poison signs on wire wickets would dot the entire neighborhood, letting us know whose yards had recently been sprayed. The only weeds seemed to be occasional clusters of dandelions and patches of clover that tried futilely to colonize the perfectly green Kentucky bluegrass. Alfred Crosby, analyzing the ways plants moved from Britain across the world, declared that “the sun never sets on the empire of the dandelion,” but to me, then, they were simply innocuous flowers, trying their best to thrive where they weren’t welcomed. It seemed senseless to me that an entire suburb would wield such heavy-handed warfare on a few stray plants. When I was fifteen, I read Silent Spring and decided to drop anti-biocide leaflets to all my neighbors, resulting in a lukewarm response from locals and some embarrassment on the part of my family. So you might say an interlude of teenage rebellion too easily dismissed enamored me of the plants we call weeds.

Bring home a copy of Dispersals today. 

But the giant hogweed indeed poses a kind of danger. In the weeks after that conservation session, I find myself telling multiple park visitors who’ve strayed into the shrubbery—one wearing only his swim trunks—that they really do want to avoid touching the plant they are about to touch. I find myself describing photosensitive burns to strangers, keeping a mental inventory of just how many times I see the plant dot this patch of East London. So why do I still feel uneasy about the plants so often derided as problems?

Later in the introduction to Weeds, Mabey offers another framing: a weed is simply “a plant in the wrong place.” This is a common phrasing and one that calls to mind the tidy definition of “dirt” offered by anthropologist Mary Douglas as “matter out of place.” In her 1966 book Purity and Danger, Douglas argues that societies with a ritual of hygiene—that is, those who have a notion of what it means for something to be dirty—are engaging in an effort to organize the environment. It is a creative act, done to create unity and meaning in our experience of the world. Douglas begins by speaking from an anthropological perspective; she contrasts European societal norms with those of other societies in ethnographic terms like “primitive” and “native.” But it becomes clear that the notions of purity and danger underpin all our acts and societal beliefs. Contemporary notions of cleanliness are informed by a knowledge of pathogens—bacteria, viruses, knowledge we’ve had for little more than a century and a half through the work of scientists like Louis Pasteur. Before that, however, we clearly had a notion of what was clean and what was dirty. Through religion and social institutions, we had a system for ordering the world, a symbolic order by which we understood what belonged where. So when we label a plant a “weed”—or to use the terms more often deployed in ecology and conservation, “invasive” or “alien”—we are not just labeling that plant. We are implying a desired order for the world at large.

So why do I still feel uneasy about the plants so often derided as problems?

But this order remains context-specific. Giant hogweed that grows in the Caucasus, where it is considered native, is no more a weed than an oak tree in England. Likewise, the specimens brought by plant collectors into Victorian gardens were, at first, seen as perfectly desirable. Japanese knotweed—a plant now considered so noxious that houses on plots where the species has taken root are often considered unsellable—was once a popular garden plant. The problem occurs when species “jump the garden wall,” to borrow a phrase from historian Harriet Ritvo. Mabey notes that even native plants like rosebay willowherb, when too persistent in their spread, might likewise be derided as weeds. The need to create order, however arbitrary, is simply a human habit: as Ritvo writes, “It is the existence of some system of classification, rather than its specific content, that is a human constant.”

But our categories are liable to transform, just as the baselines of our knowable world have shifted. As the climate changes, researchers now predict that giant hogweed’s range will decrease by the middle of our century. This is not to say it will no longer be invasive; rather, needing cold winters, the hogweed will move northward. Its presence is not a given, but in the context of anthropogenic climate change, we are reminded that we cannot remove ourselves from the story of this plant’s invasiveness. Weediness implies movement, but plants do not often move very far without our blessing.


In late summer, we leave East London and move into a rented house in Cambridge so I can be closer to work. The landlord’s mother pops by to check on the garden. Mostly, I think, she is gauging my willingness to tend it. She takes inventory of the front garden’s shrubbery, teeters from a ladder as she trims back the neighbor’s wisteria growing pleasantly over our doorway. Once she is finished, she points to a bare patch of low growth amidst the landscaped sections of the garden. She has laid down a weed-resistant membrane, which glows black in the September sun.

“There used to be a buddleia here,” she remarks. “But the last tenants tore it out.” She frowns, her eyes searching mine for a reply.

“Such a pity!” I say, almost automatically, noting silently that the absence of the plant will bring more afternoon sun into the living room. I don’t want to tell her that I’m not bothered by the weeds inching their way through the membrane, that in fact I somewhat like the persistent, irregular patch of growth. But I know, too, that in our row of houses, an untended patch would stick out sorely. That not everyone cares for weeds as I do.

It isn’t until months later that I decide to take inventory. I slip into the morning shade and begin to count species that have forced their way through the membrane: evergreen bugloss, cheeseweed mallow, wild teasel, and horseweed. Dead-nettles and dock grow somewhere in between, and dandelions, too. The green stands knee-high, reaching for the sun that stripes the front garden in gold each day. I know some neighbors may not appreciate the teasel, though I love the birds it brings. A few brown spiky stalks remain of last year’s seed heads, so it will have spread itself around next door’s garden, too. I had thought to pop some pots out here—I’ve started too many tomatoes and they’d appreciate the west-facing light—but now I wonder if I should actually “weed” the patch. Whether I should lay down native wildflower seeds, or find a way to make the patch look tended. I’ve come to admire this bit of green outside my window. It is the view from my desk, the ragged growth I look upon while I write. What plants, I ask, do I want to think with?

Excerpted from Dispersals: On Plants, Borders, and Belonging, copyright © 2024 by Jessica J. Lee. Reprinted by permission of Catapult.

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Jessica J. Lee is a British-Canadian-Taiwanese author, environmental historian, and winner of the Hilary Weston Writers’ Trust Prize for Nonfiction, the Boardman Tasker Award for Mountain Literature, the Banff Mountain Book Award, and the RBC Taylor Prize Emerging Writer Award. She is the author of Turning, Two Trees Make a Forest, Dispersals, and the children’s book A Garden Called Home, and co-editor of the essay collection Dog Hearted. She is the founding editor of The Willowherb Review and teaches creative writing at the University of Cambridge. She lives in Berlin.