In 1999, British radiologist Nicola Strickland went on holiday with a friend to the Caribbean island of Tobago. While exploring a deserted beach looking for seashells, the pair came upon a number of small, round, yellow-green fruits scattered among the fallen coconuts and mangoes. Intrigued, they decided to try the fruits and found them to be pleasantly sweet. But that pleasure was not to last. In a 2000 article in the British Medical Journal, Strickland describes what happened next:

“Moments later we noticed a strange peppery feeling in our mouths, which gradually progressed to a burning, tearing sensation and tightness of the throat. The symptoms worsened over a couple of hours until we could barely swallow solid food because of the excruciating pain and the feeling of a huge obstructing pharyngeal lump.

Over the next eight hours our oral symptoms slowly began to subside, but our cervical lymph nodes became very tender and easily palpable. Recounting our experience to the locals elicited frank horror and incredulity, such was the fruit’s poisonous reputation.”

Indeed, Strickland and her friend were extraordinarily lucky to survive their ordeal, for the tree the innocuous-looking fruit had fallen from was none other than the Manchineel, a plant so extraordinarily toxic that one cannot touch it, shelter beneath it, or even breathe the air around it without entering a world of hurt. It is widely considered to be the most dangerous tree in the world.

Hippomane Mancinella, also known as the “Beach Apple” or, in Spanish, Manzanilla de la Meutra – the “little apple of death” – is a small shrub-like evergreen tree native to southern Florida, the Caribbean, Mexico, Central America, and northern South America. Reaching up to 15 metres in height, it is mostly found on beaches or in brackish swamps, where it often grows between mangrove trees. Manchineel is a member of the Spurges, a large family of plants that includes the holiday poinsettia. But while, contrary to popular belief, eating a poinsettia will not hurt you nor your pets in the slightest, the Manchineel packs an altogether nastier punch. Every part of the tree, from the roots to the leaves, is filled with a milky, latex-like sap containing a deadly cocktail of toxins including phorbol, hippomanin, mancinellin, apogenin, phloracetophenone, and physostigmine. Of these, perhaps the nastiest is phorbol, a highly caustic chemical which on contact with the skin inflicts large, painful blisters and if splashed in the eyes induces temporary blindness. Even breathing the air close to the tree is enough to cause slight lung damage. Phorbol is also highly soluble in water, meaning that anyone foolish enough to shelter under a Manchineel tree during a rainstorm is likely to get soaked head to toe in the botanical equivalent of WWI mustard gas. In fact, phorbol is so corrosive it has even been known to peel the paint off of cars.

If ingested, the other toxins in the Manchineel’s sap and fruit can induce severe throat pain and swelling, vomiting, excruciating intestinal pain, psychological disturbances, and even death. Indeed, the tree’s scientific name, Hippomane Mancinella, literally translates to “the little apple that drives horses mad.” Among the many toxins found in the tree, one, physostigmine, is also found in the Calabar bean, which for centuries was used by the Efik people of south-east Nigeria as an ordeal poison. According to Efik custom, a person accused of witchcraft would be made to drink a mixture of crushed-up Calabar bean and water; if they died, they were guilty, but if they survived – usually by immediately vomiting up the poison – they would be declared innocent and released.

If by now your reaction to the big pile of “nope” that is the Manchineel tree is to yell“kill it with fire!” unfortunately you are once again out of luck, as the smoke from burning the tree can inflict severe damage to the eyes and lungs. Point Manchineel tree…

The toxic properties of the Manchineel have been known for centuries, the sap being used as a weapon by many Caribbean tribes such as the Arawak, Taino, Carib, and Calusa. Indeed, it was a Calusa arrow tipped with Manchineel sap which reportedly killed Spanish Conquistador Juan Ponce de Leon during a skirmish in Florida in 1521. There are also reports of tribes tying their enemies to the trees as a form of torture. But not all the tree’s uses were so violent; the dried sap and fruit, for example, are used in traditional medicine to treat edema and urinary issues. And incredibly, despite its dangerous reputation Manchineel wood has also been used for centuries by Caribbean carvers and cabinetmakers. As cutting the trunk with an axe is too dangerous, the tree must instead be burned at the base – with the collector, one assumes, standing far, far away – and the wood dried in the sun for several days to destroy the toxins in the sap.

Among the first Europeans to encounter the Manchineel tree was Christopher Columbus, who gave it its traditional name of “little apple of death” and described its effects on sailors who accidentally ate its fruit or cut down the tree for firewood. The tree was also commonly encountered during the Golden Age of Piracy and appears in the memoirs of many 17th and 18th Century buccaneers such as Basil Ringrose and William Stephens as well as in the diary of William Ellis, the surgeon on Captain James Cook’s last voyage.

At this point you may be wondering: how on earth did the Manchineel evolve to be so horrifically toxic? After all, most fruit-bearing trees depend on their fruit being eaten by animals in order to spread their seeds. But with the sole exception of the Black-Spined Iguana, which is even known to live among the tree’s branches with no ill effects, the Manchineel is toxic to nearly every known animal. As it turns out, the Manchineel has no need of animals as, by virtue of growing near water, its buoyant fruit are easily dispersed by ocean currents in the same manner as coconuts. Thus the tree’s extreme toxicity is likely as it poses no obstacle to its reproduction while ensuring that any potentially destructive animals keep far, far away.

Today the Manchineel is an endangered species, but rather than being exterminated like the demon spawn it is, the tree is protected as its roots help to stabilize the soil and protect shorelines from erosion. Consequently, Manchineel trees in areas accessible to the public are often clearly marked with red paint,  small fences, or explicit warning signs to make sure nobody goes anywhere near them. While no deaths from eating Machineel fruit have been confirmed in modern times, dozens of cases of burns and blindness due to contact with its sap are reported every year. So if ever you are on a Caribbean holiday and come across a small tree with reddish bark, spear-shaped leaves, and small yellow-green fruit. Don’t even think about it. Just walk away.

If you liked this article, you might also enjoy our new popular podcast, The BrainFood Show (iTunes, Spotify, Google Play Music, Feed), as well as:

• Do Trees Poop and Pee?
• How Do Trees Get Water from the Ground Up to Their Leaves?
• The Curious Case of the Tree That Owns Itself
• The Murder Tree
• What Ever Happened to All the Moon Trees

Bonus Fact:

A contender for the most dangerous tree in the world is one known colloquially as “The Murder Tree”.

Cerbera odollam is a small hardwood tree (see our video, How Do They Differentiate Between Hardwood and Softwood Trees? really, that title sounds boring and obvious but it’s actually not what you think and is super fascinating; I promise…) that can, under favourable conditions grow to around 10 metres in height and is endemic to India and south-east Asia. Despite its unassuming appearance, the tree hides a deadly secret inside of the husk that contains its seeds. These seeds contain a cardiac glycoside called, cerberin. Cerberin is incredibly toxic in relatively low dosages, often killing its victims within a few hours, during which time they may suffer crippling stomach pain, diarrhea, irregular heart rhythm, vomiting and sometimes a splitting headache. Eventually, once enough of it accumulates in your system, the cerberin will succeed in completely inhibiting the cellular “sodium/potassium pump” enzyme (Na⁺/K⁺-ATPase), screwing with the heart’s electrical system and ultimately stopping it dead, very similar to how lethal injections in the United States work. And for reference, a single cerbera odollam seed contains a lethal dose of cerberin for a typical adult human.

While accidental ingestion of the inner seed is not completely unheard of, due to the fruit produced by the cerbera odollam being edible, if a little bitter, it is commonly used for murder and suicide in Indian coastal towns which border the sort of marshy swampland the tree likes to grow in. Exactly how many people are killed each year due to someone having their food intentionally spiked with cerbera odollam seeds isn’t clear because the poison produced by it doesn’t show up on normal toxicology reports, and is relatively unknown in many regions of the world. This has led some experts, such as French Toxicologist Yvan Gaillard, who published the results of a decade long study on this very topic in the Journal of Ethnopharmacology, to describe the plant as being “perfect” for murder. You see, most toxicologists, even if they’ve heard of the plant, will only test for cerberin poisoning if there’s a strong suspicion the victim consumed something containing it prior to their death, because testing for cerberin poisoning is rather costly and requires the use of “high-performance liquid chromatography coupled with mass spectrometry” to detect with any degree of certainty- something that is not an option in many regions anyway. Of course, those toxicologists who haven’t heard of it would never know to check.

Because of this, the amount of deaths caused by cerbera odollam poisoning is uncertain. That said, based on the documented instances that are known (which likely make up a small percentage of the actual total), the plant is responsible for at least a death per week in the South Indian state of Kerala alone, where the plant grows wild and in abundance and is responsible for an estimated 50% of plant poisoning cases annually in the region.

You might wonder why a person being poisoned with such a seed wouldn’t taste it, given its bitter flavour, but the seeds can easily be masked by putting them into a dish containing something like chilies that are prevalent in Indian cuisine. The taste can also be masked with sugar, and the vast majority of suicides committed via ingestion of the seeds is done by removing the seed from the outer husk, then crushing and mixing it with raw cane sugar. “Just a spoon full of sugar helps the medicine go down” and all that. Not the most pleasant way to die, but given it’s freely available in places like Kerala, and has a relatively certain outcome, it remains extremely popular.

Interestingly, with the limited data we do have (including suicides and murders), it’s noted that 75% of people who die via ingesting the cerbera odollam seeds are women. Researchers at the Laboratory of Analytical Toxicology in La Voulte-sur-Rhône speculate that this massive gender discrepancy is because the plant is being used to poison newly married wives “who do not meet the exacting standards of some Indian families“. However, beyond the murders, young women are also statistically much more likely to use the cerbera odollam seeds to commit suicide; such was the case in May of 2015 when four young girls consumed cerbera odollam seeds as part of a suicide pact after being abused at an athletic training camp. That said, it should be noted that in the Western world, while about four men will commit suicide for every one woman, nearly three times as many women as men will attempt to kill themselves. If the popular method of suicide in the Western world was using something like cerbera odollam seeds where death is almost certain, it could potentially skew those tragic numbers significantly to be somewhat more inline with the Laboratory of Analytical Toxicologies data for Kerala, India.

Whatever the case, the prominent use of this plant in suicides and murders has led to local governments trying to find new uses for this natural resource. Particularly in impoverished areas, if the seeds have marketable uses, it’s literally money growing on trees for any of the populace who wants it, making the seeds less readily available as they’re harvested en masse- so less death and more money in the local economy. Towards this end, in recent years the seeds have begun being harvested for use in various products like bio-insecticides and rat poison, among other things. In Kerala, where the plant is responsible for more deaths than anywhere else on Earth, locals can earn a decent living dehusking the plant with their bare hands in various processing yards across the state. We bet lunch hour at those places is really tense…