Though most of us know we shouldn't make meals out of strange plants we come across in the wilderness, we probably wouldn't think twice about touching those with shiny fruit and appealing colors, assuming them to be as safe as they are beautiful. But there are many trees, flowers, and berries that can cause great bodily harm through mere contact—agonizingly itchy rashes, respiratory issues, temporary blindness, and even total organ failure. While some fatal flora have to get inside your body to kill you, others are so dangerous that you probably shouldn’t even stand next to them. Here are some of the most notorious.
1. MANCHINEEL TREE
The manchineel, or Hippomane mancinella, is a relative of the poinsettia and holds the Guinness World Record for “most dangerous tree.” Pretty much every part of this plant—which is native to Florida, as well as parts of the Caribbean and Central and South America—is out to get you: Its fruits are known in Spanish as manzanilla de la muerte, or “little apple of death,” and its sap, once used to poison arrows, contains the toxin phorbol, a carcinogen. Contact with the sap causes a blistering, painful rash that can last for weeks, which means you don't want to stand under the tree in a storm; raindrops can pick up the sap and drop it onto your unprotected skin. You shouldn't try to destroy the manchineel, either—inhaling smoke from burning its leaves can lead to respiratory issues or even temporary blindness. According to the Florida Institute of Food and Agricultural Sciences, “interaction with and ingestion of any part of this tree may be lethal.”
2. ROSARY PEA
The rosary pea (Abrus precatorius), also known as crab’s eye or jumbie bead, is a perennial climbing vine whose small seeds are astonishingly deadly: They contain a toxic protein called abrin that is so poisonous, a single seed can kill you within 36 hours. In the tropical regions where they're found, rosary peas are also used to make jewelry, because nothing says “pretty necklace” like possible death.
The good news is that simply handling a rosary pea seed won’t be fatal; the hard coating surrounding the seeds, which are usually bright orange or red with a black spot, needs to be broken for poisoning to occur by inhalation or absorption. You’ll even survive swallowing one. Chew it, however, and you’re in for a fun ride of vomiting, liver failure, and death. The rosary pea’s most common victims are children and, well, jewelry makers: Prick a finger while drilling a hole in the small seed, and that necklace will be your last.
Don't let its cutesy name or heart-shaped foliage fool you: The gympie-gympie (Dendrocnide moroides) is not to be trifled with. The leaves and fruits of this poisonous nettle, native to Australia, Indonesia, and the Moluccas, are covered with hollow stinging “hairs” shaped like hypodermic needles that are notoriously difficult to remove from skin. Moroidin, the neurotoxin found in the gympie-gympie plant, causes painful itching so excruciating that it’s been known to drive humans mad with agony. Simply breathing near the plant can cause nosebleeds and rashes due to the inhalation of shed needles.
“The first thing you’ll feel is a really intense burning sensation and this grows over the next half hour, becoming more and more painful,” virologist Mike Leahy describes in a video in which he intentionally stings himself with the gympie-gympie. “Shortly after this, your joints may ache, and you might get swelling under your armpits, and that can be almost as painful as the original sting. In severe cases, this can lead to shock, and even death. And if you don’t remove all the hairs, they can keep releasing the torturous toxins for up to a year.”
Entomologist and ecologist Marina Hurley describes coming in contact with a plant—which she did many times—as “being burnt with hot acid and electrocuted at the same time.” And even with repeated exposure, your system never adapts; symptoms only get worse over time. The pain is so bad that during WWII, an Australian army officer reputedly killed himself after realizing he had accidentally used the plant’s leaves as toilet paper.
It's also worth noting that age doesn't diminish the danger: Dry samples, preserved for decades, still retain their stinging abilities.
Aconite (Aconitum napellus), more commonly known as wolfsbane, is a flowering perennial that grows in mountain meadows in the Northern Hemisphere. Like the manchineel tree, it has historically been used to poison arrowheads for hunting. Aconite contains large quantities of pseudaconitine, a toxin that can paralyze an animal as large as a whale, allowing it to be brought down by hunters.
Like the manchineel tree, wolfsbane causes its fair share of accidental deaths. In 2014, a gardener in Hampshire, England, was rushed to the hospital after handling the plant without protective clothing. The toxin entered his blood, causing multiple organ failure, and within five days, he was dead. Chelsea Physic Garden representative Tom Wells calls wolfsbane one of the most dangerous plants found in Britain’s gardens: “The roots are where the highest level of poison is found, although it is still found in the flower. If there were cuts on his hand, it would enter his bloodstream and affect his heart very quickly,” causing arrhythmia or paralysis.
5. BUNYA PINE
The Bunya pine (Araucaria bidwillii) kills with an even more brutal touch, though at least it's not intentionally trying to murder people. Growing up to 130 feet tall in the rainforests and mountains of Australia, the ancient pine (dating back 350 million years) produces massive, watermelon-sized cones weighing up to 22 pounds … which it then drops on unsuspecting victims below.
“These huge pine cones have the capacity to be lethal if they were to fall on someone passing underneath from such a large height,” Baw Baw Shire Council Mayor Diane Blackwood said in 2012, when a Bunya pine planted by a restaurant troubled local residents. According to The Conversation, many councils rope off areas by the pines or erect warning signs during “cone season.” If you’re ever in Australia between December and March, watch your head.
6. WHITE SNAKEROOT
White snakeroot (Ageratina altissima) is a herbaceous perennial native to eastern and central North America that was responsible for the deaths of thousands of European settlers in the 19th century. Consumed by cows and other livestock, the plant's leaves and stems contain a toxin called tremetol that was passed on to humans through the animals' milk. This “milk sickness” manifests as vomiting, tremors, liver failure, constipation, delirium, and often death—of both humans and calves who drank the tainted milk. Perhaps the most famous victim of white snakeroot was Nancy Hanks Lincoln, mother of President Abraham Lincoln. Modern animal husbandry practices have mostly made milk sickness a thing of the past; the plant is cleared so animals can't graze on it.
Oleander (Nerium oleander) is widely cultivated and flourishes in subtropical and mild oceanic climates. The flowering evergreen shrub is prized by gardeners and usually grows to 6 to 12 feet tall. It’s also chock full of toxins. Cardiac glycosides called oleandrin and neriine are found in oleander’s flowers, leaves, roots, and fruit, and while similar compounds are used to treat heart failure by helping the muscle to pump blood, oleander can also stop your heart. (Additional symptoms include skin rashes, visual disturbances like blurred vision and halos, and bloody diarrhea.) The good news is that you’ll likely vomit immediately after ingesting the plant, giving you a second chance at life. Those with hardy stomachs, beware.
8. GIANT HOGWEED
The invasive giant hogweed (Heracleum mantegazzianum) grows all over the world, from Europe to Australia, and its corrosive sap contains the phototoxin furocoumarin. Touching the plant followed by any exposure to ultraviolet light causes a reaction called phytophotodermatitis, a rash so severe it is often mistaken for chemical burns. It can also cause permanent blindness if the photosensitive chemicals come in contact with your eyes. The giant hogweed's effects are insidiously long-lasting: Blisters from the rashes and third-degree burns it inflicts can take months to heal, and the affected area may remain photosensitive for years after exposure.