Cerbera odollam: “The Suicide Tree” That Harms and Heals

The latest season of HBO’s The White Lotus transports viewers to Thailand, where the misfortunes of wealthy guests and staff at a fictional resort reveal the dark side of paradise. In the season premiere, the eldest son of the Ratliff family toys with a light green, mango-like fruit that had fallen from a poolside tree.

“I wouldn’t eat that,” cautions Pam, a hotel employee. “That is the fruit of the mighty pong-pong tree, and the seeds of the fruit are toxic.”

Her warning, though intended to keep the Ratliffs safe, plants the seed for a pivotal event in the satire’s shocking finale, which aired early last month. The episode casts a spotlight on a tree implicated in thousands of deaths across history—many of which were intentional. The poisonous kernels of Cerbera odollam, often referred to as the pong-pong tree, have earned the plant a far more menacing nickname: “the suicide tree.”

Cerbera odollam is native to South and Southeast Asia, the Pacific Islands, and Queensland, Australia. The tree grows up to twelve meters tall (nearly forty feet), typically along coastlines and riverbanks. With a bushy crown of narrow, glossy green leaves and fragrant white flowers, the species is cultivated and distributed beyond its native range as an ornamental shade tree.

The pong-pong tree may appear harmless, but it bears forbidden fruit. Each fruit contains one or two large seeds filled with concentrated toxins that, when consumed, attack the heart. The seed’s most potent toxin, cerberin, disrupts the molecular pumps that regulate cardiac movements. Nausea, vomiting, and diarrhea constitute the body’s first line of defense against cerberin ingestion. However, when attempts to purge the poison are unsuccessful and time passes without treatment, the heart begins to fail.

“Assuming that the person doesn’t receive any treatment at all, death can come within an hour,” explains forensic science professor Hilary Hamnett in an interview with journalist Becky Ferreira. “When people who’ve taken this thing go to the hospital, typically their heart rate might be at 30 beats a minute.”

Much of the Western world is unfamiliar with Cerbera odollam, but those residing in its native range are well aware of the risks. The poisonous kernels are responsible for a significant number of suicides and homicides, particularly in rural areas of South Asia. In the Indian state of Kerala, for example, an average of fifty deaths per year are attributed to the tree.

“To the best of our knowledge, no plant in the world is responsible for as many deaths by suicide as the odollam tree,” writes the team that evaluated the prevalence of Cerbera odollam poisonings in Kerala.

The toxic seeds also played a role in generations of “trial by ordeal” rituals. These painful, often lethal, experiences sought to determine the guilt or innocence of an individual. Until the mid-nineteenth century in Madagascar, the seeds of Cerbera odollam and its close relative Cerbera manghas were ingested by the accused or an animal proxy. Death implied guilt, while survival signaled innocence and supernatural intervention.

“Some people survived, not because they were innocent of wrongdoing,” reflects chemical biologist Jing-Ke Weng in an interview with journalist Cesareo Contreras. “They were just a bit luckier, had a little bit of a smaller dose, or maybe they had a metabolism that can detoxify this toxicity.”

While trial by ordeal has been outlawed in Madagascar, the use of pong-pong seeds for murder and suicide persists, largely in India and Southeast Asia. The rate of poisoning appears to be increasing, and deaths caused by seed ingestion are likely underreported. According to researchers, “Upon autopsy, death by heart failure would be attributed to natural causes unless the pathologist had a reason to suspect poisoning.” Furthermore, the lab techniques used to identify Cerbera odollam toxins in tissue samples aren’t always readily available.

Fortunately, studies of patients hospitalized for ingesting Cerbera odollam show that recovery is possible if the poison is identified and treated in time. In 2016, for instance, researchers reported an 88 percent survival rate for fifty consecutive cases of pong-pong poisoning at a tertiary care center in Kerala.

Interestingly, medical practitioners often counteract the effects of suicide tree ingestion with the product of another notorious plant: Atropa belladonna, otherwise known as “deadly nightshade.” This medium-sized shrub with dark green leaves and purple, bell-shaped flowers is highly toxic, containing tropane alkaloids that interfere with the nervous system. The plant’s enticing black berries pose the greatest danger, as they may be accidentally consumed by children or misidentified by foraging adults. In the 1597 edition of his Herball, English naturalist John Gerard wrote of the species: “Banish it from your gardens and the use of it also, being a plant so furious and deadly.”

But Atropa belladonna is more than an agent of death. In 1819, chemist Rudolph Brandes isolated a compound from the belladonna root that we still use in medicine today. The alkaloid, called atropine, is administered to increase heart rate, reduce saliva and fluid in the respiratory tract during surgery, and treat insecticide or mushroom poisoning. Too much atropine can be lethal, but low doses of the compound are key to treating Cerbera odollam ingestion.

Like deadly nightshade, the suicide tree isn’t exclusively harmful. Ethnobotanical records describe how other parts of the plant have been used in traditional medicine. According to ethnobotanist Wayne Arthur Whistler, communities in the Cook Islands applied Cerbera odollam sap to the skin as a treatment for severe rheumatism. In “Ethnomedicine in the Tongan Islands,” Lisa O’Rourke George describes how pong-pong tree leaves were used in eye and ear drops to treat headaches, macerated for pain-relieving head massages, and applied to boils. She also writes that the bark was used as a laxative and in infusions for abdominal pain.

So, the pong-pong tree is best known for its capacity to kill, but the plant is not without medicinal virtue. Several toxic plants possess this duality, with compounds that can both harm and heal. After all, the word “pharmacy” derives from the Greek pharmakon, which can refer to either a remedy or a poison. The Dumbarton Oaks Plant Humanities Initiative seeks to unearth the histories of species like Cerbera odollam, unraveling the complex ties between humans and the plant world.

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