Science & Technology

Giant Hogweed Is the Skin-Burning, DNA-Attacking Plant of Your Nightmares

There's something out there — something dangerous. It's an invader, and it's spreading faster than we humans can contain it. All it needs to do is touch you, and your skin will start to blister and peel. Even worse, it will attack the very building blocks of your DNA. But this isn't John Carpenter's "The Thing." It's just another deadly plant: the giant hogweed. Watch out!

Giant hogweed in England.

Die on the Hog

Giant hogweed isn't new in the United States, but it's spreading. It has been here since 1917 when New Yorkers brought it over to the Big Apple to decorate their gardens. Sure, why not? What could go wrong? It's not as if a pretty white flower can grow into a massive, flesh-mutating monstrosity, right? Right?

You already know where this is going, but let's just run down the facts. Giant hogweed really puts the emphasis on "giant." It looks a bit like Queen Anne's Lace, but where that harmless plant is only 4 feet (1.2 meters) tall or so, giant hogweed can grow as high as 20 feet (6.1 meters). Of course, it's not the size that makes the hogweed dangerous. It's the sap. Brushing up against the plant can expose you to chemicals known as furocoumarins — they're phototoxins, meaning they can be dangerous when exposed to light. If that happens, electrons from the toxins bind to the DNA bases thymine and cytosine, preventing them from enabling basic cellular function. Within 15 minutes, your skin can start to blister and peel as if from the worst sunburn of your life.

In Virginia, where giant hogweed plants were discovered for the first time this year, a teenage landscaper was recently severely injured after he cut down a plant not knowing what it was. His recovery may take quite some time. As Alex Childress told People, "I can't go out into the sun for anywhere from two to six months. My face could be sensitive to light for a year up to two years." Of course, his was a quite severe case — if all you've done is brush against a plant, just wash the affected area with soap and cold water, and try to avoid the sun for two days.

A Less Poisonous Past

The United States isn't the only place where giant hogweed has been spreading like, well, a weed. The plant originated in the Caucuses, but spread across continental Europe, the British Isles, across the ocean to the States, and across another ocean to Australia and New Zealand (generally by gardeners without a lot of foresight). But once it's established itself in a place, it spreads with impunity. Its giant size makes it take up a lot of resources that could have been used by its gentler competitors, and every giant hogweed produces more than 100,000 seeds per year. But that all begs the question: Why is there such a panic over giant hogweed right now?

It's not the first time the plant has stepped into the spotlight as a threat to public health. Writing for The Guardian, Jane Perrone notes that a similar panic occurred in 1970, even though the plant had been a fixture of the English countryside since the 19th century. So where were all the reports of blistered unfortunates from the decades previous? Experts have a few ideas.

It could be that 1970 and 2015 (the year the article was written) were both "vintage years" for giant hogweed in the UK, meaning it was particularly widespread so more people could encounter it not knowing the risks. That seems to match up with what's going on in the USA right now since the plant certainly seems to be booming this year as it expands its territory. There's also the simple fact that modern people may have less botanical knowledge in general. Maybe the kids of those 1917 gardeners knew the risks that giant hogweed posed ahead of time and simply didn't take their chances. In any case, one thing is clear: If you encounter a towering white flower on your next nature hike, steer clear.

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Written by Reuben Westmaas July 24, 2018

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