Giant Hogweed (Heracleum mantegazzianum)

*leans into Taco Bell drive-thru mic* The world is a vampire

Plants have been responsible for a lot of what was thought to be supernatural activity over the years. An outbreak of ergot in rye, for example, is thought to have been the cause of the strange behavior exhibited by the “witches” accused in the Salem witch trials. The giant hogweed (heracleum mantegazzianum), for its part, could do an awful lot to convince bystanders that you were a vampire.

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A note on plant toxicity

Wherever possible, when speaking on plant toxicity, I’ve used information from official government sources like poison control center studies or the CDC. I can only vouch for its accuracy inasmuch as it comes from authorities on the matter.

If you or someone you know ingests a plant you believe to be poisonous, contact 911 or your equivalent local emergency medical service.

PoIR Holiday Special: Mistletoe and Poinsettia


It’s the most poisonous time of the year…or is it?

The holiday season is a time to celebrate, and we do that by killing a bunch of plants and hauling out our favorite dead ones as decorations. We’re savage killers, basically, and if you believe what you’re told, you might also think the same of some of our most cherished holiday plants! In the Plants of Ill Repute Holiday Special, we’ll be looking at two such plants — the common mistletoe (Viscus album) and the poinsettia (Euphorbia pulcherrima) — and see which Christmastime rumormongers should get coal in their stocking.

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Killer algae (Caulerpa taxifolia)

Seafaring super-soldier.

Some plants are born bad. Some are just fine where they originated, but when introduced to other ecosystems, become horrible monsters. And some turn to a life of crime against their will. The tropical seaweed Caulerpa taxifolia was a fairly innocuous plant used in aquariums, but some combination of chemicals and exposure to UV light caused a genetic mutation in the taxifolia in a German zoo.

This new strain grew quickly and flourished in the normally stifling cold water of the aquarium, and before long other aquariums wanted to get a hold of this special strain to fill their own tanks. It made its way to Jacques Cousteau’s Oceanographic Museum in Monaco, where an employee dumped waste from a tank inhabited by C. taxifolia into the ocean instead of a designated area. 

Soon, it was everywhere. 

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Khat (Catha edulis)

A harms race.

Finding a way into Somalia wasn’t easy for author Mark Bowden, who needed to visit the country to research his book Black Hawk Down (on which the movie of the same name was based). The solution he eventually came upon was flying in on a plane normally reserved for transporting the narcotic plant known as khat (Catha edulis, family Celastraceae) and paying the market price for the two hundred pounds or so of khat he displaced. Ironically, the drug he sat in for played a role in the violence that befell the soldiers in the Black Hawk helicopters that were shot down in Mogadishu in 1993 — the very incident that inspired his book in the first place.

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Water hyacinth (Eichhornia crassipes)

No man is an island, but this plant is.

It’s easy to forget that plants don’t only grow in dirt. There are plenty of plants that grow in water, and they have the same capacity for help and harm as terrestrial plants too. There are seeds and even weeds, and they can be quite troublesome, given the delicate nature of aquatic ecosystems.

In fact, they can be even worse than land weeds. Eichhornia crassipes, the water hyacinth, is so horrendous, grows so fast, and ruins aquatic ecosystems so thoroughly that it currently holds the Guinness World Record for “World’s Worst Aquatic Weed.”

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Suicide tree (Cerbera odollam)

For when life is just nuts.

Many plants I’ve discussed here are poisonous. They have the capacity to kill with the dangerous compounds they contain, most often against unwilling targets. But they can also be used on the willing, and many are exceedingly effective in that regard. So effective that, in certain cultures, that capacity to assist one in killing oneself becomes the plant’s whole identity.

A lovely, fragrant tree native to southeast Asia and India’s Kerala region has a common name that should be enough to clue you in to its most notorious use. Enter Cerbera odollam, the suicide tree.

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Ever thought of covering the Devil's Club (Oplopanax horridus)? It's another nettle-type plant, and is very nasty to run into. —by Anonymous

Devil’s club (or devil’s walking stick) is a really cool plant, and not because it’s dangerous. There’s not a lot to write about in terms of what we normally cover here — it has brittle spines that hurt like you’d expect brittle spines to hurt — but it has other neat qualities, like how weird it looks and how long it takes to fully form and reproduce. Compared to other plants, its growth and reproduction rate is glacial, and it just hasn’t learned to deal with human contact like other plants have over time. It’s basically primordial.

Mala mujer (Cnidoscolus augustidens)

Watch out boy, she’ll chew you up.

Plants that cause pain tend to specialize based on their family. The nightshades of the Solanaceae family, for example, have their potent poisons when ingested. Others, like the nettles in the Urticaceae family, deliver pain with stinging hooks and nettles. Mercifully, few plants double up on their pain-inducing mechanisms. Don’t expect that courtesy from every plant, though, or you’ll end up with the scorn of one mala mujer, the  Cnidoscolus angustidens.

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