Every year, an estimated 100,000 people in the United States fall victim to plant poisonings.1 The world is home to an array of dangerous and even deadly flora.
While many of these plants are known for their beauty or medicinal properties, they also harbor potent toxins capable of causing severe illness or death.
Here are 14 of the world’s most dangerous trees and plants, their unique characteristics, ecological roles, and the risks they pose to unsuspecting humans.
1. Manchineel Tree (Hippomane mancinella)
The manchineel tree, native to Florida and the Caribbean, is considered the most dangerous tree in the world by the Guinness World Records. (ref) Every part of this tree is highly toxic, from its bark and leaves to its fruit, which resembles a small green apple.
The sap of the manchineel tree is so poisonous that even standing under the tree during rain can cause severe blistering of the skin.
Ingesting the fruit of the manchineel tree can be fatal, causing intense burning and swelling of the throat, as well as potentially severe digestive issues. The smoke from burning manchineel wood can cause temporary blindness if it comes into contact with the eyes.
Despite its highly toxic nature, the manchineel tree plays an important ecological role, helping to prevent soil erosion with its deep-growing roots.
2. Suicide Tree (Cerbera odollam)
The suicide tree is a highly poisonous plant found in India and parts of Southeast Asia. It gets its ominous name from the fact that people have used its toxic fruits to take their own lives.
The seeds contain cerberin, a potent compound that disrupts the heart’s electrical activity, leading to fatal arrhythmias.
Despite its deadly properties, the suicide tree is often planted as an ornamental hedge in gardens due to its attractive appearance. The seeds are also used to make industrial rat poison and insect repellents.
It is estimated that the suicide tree is responsible for up to 500 fatal poisonings in just one state in southwest India.
3. Bunya Pine (Araucaria bidwillii)
The bunya pine, a living fossil that has existed since the time of the dinosaurs, is found almost exclusively in Queensland, Australia.
While the tree itself is not poisonous, it poses a significant threat due to its massive cones, which can weigh up to 40 pounds and fall from great heights.
These falling cones have been known to cause serious injuries and even fatalities to unsuspecting people standing beneath the tree.
However, the bunya pine has also been an important food source for indigenous tribes for hundreds of years, with the nuts from the cones being consumed during special gatherings and ceremonies.
4. Milky Mangrove (Excoecaria agallocha)
The milky mangrove, also known as the blind-your-eye mangrove, is a tree species found in the coastal regions of Australia. The tree’s sap contains powerful irritants that can cause severe skin blisters and temporary blindness if it comes into contact with the eyes.
However, the milky mangrove plays a crucial role in protecting shorelines from damaging storms, hurricanes, and floods.
Its timber is also used in canoe construction due to its soft and lightweight nature, and the tree provides a habitat for various marine and terrestrial wildlife species.
5. Oleander (Nerium oleander)
The oleander, a popular ornamental, contains several toxic compounds, including cardiac glycosides, saponins, and oleandrin. Ingesting any part of the plant can cause symptoms such as nausea, vomiting, dizziness, and potentially fatal heart arrhythmias.
Oleander has been used in traditional medicine for centuries despite its toxicity. However, there is no scientific evidence to support its efficacy in treating human diseases.
The plant’s toxins are so potent that even honey made from oleander nectar can be poisonous.
6. Sandbox Tree (Hura crepitans)
Native to the Amazon rainforest, the sandbox tree is known for its unique defense mechanism. The tree’s trunk is covered in sharp spines, and its sap can cause severe skin irritation and rashes upon contact.
The sandbox tree’s fruit is equally dangerous. When mature, the fruit explodes, launching its seeds at speeds of up to 150 mph, potentially injuring anyone unfortunate enough to be in its path.
Despite these hazards, the tree’s timber is valued for its durability and strength.
7. European Yew (Taxus baccata)
The European yew, found across Europe, North Africa, and Southwest Asia, contains a potent toxin called taxine in all parts of the tree except for the red berry surrounding the seeds.
Ingesting any part of the yew can lead to severe poisoning and potentially death.
Historically, yew wood was prized for its strength and durability, often used to make bows and tool handles. The Clacton Spear, a 400,000-year-old wooden spearhead made from yew, is one of the oldest known wooden artifacts.
8. Strychnine Tree (Strychnos nux-vomica)
The strychnine tree, native to the Indian subcontinent, is the primary source of the highly toxic alkaloid strychnine.
This potent compound affects both the nervous and muscular systems, causing painful muscle contractions and potentially fatal respiratory paralysis.
Strychnine has been used in small doses as a treatment for various ailments, including eye disorders and snake bites. However, the therapeutic use of strychnine is now largely obsolete due to the availability of safer alternatives.
9. Black Locust (Robinia pseudoacacia)
The black locust, native to the eastern United States, is a fast-growing tree known for its durable and rot-resistant wood.
However, all parts of the tree, especially the bark, and seeds, contain toxic compounds called robin and robitin, which can cause severe digestive issues and potentially fatal poisoning if ingested.
The black locust has been widely planted for its ability to fix nitrogen in the soil and prevent erosion. The tree’s wood is also valued for its strength and durability, and it is often used in fence posts, furniture, and flooring.
10. Gympie Gympie Tree (Dendrocnide excelsa)
The Gympie Gympie tree, also known as the stinging tree, is found in the rainforests of northeastern Australia. The tree’s leaves and stems are covered in tiny, hollow, silica-tipped hairs that can penetrate the skin and inject a potent neurotoxin.
Contact with the Gympie Gympie tree causes immediate, intense pain that has been described as feeling like being burned with hot acid and electrocuted simultaneously.
The pain can last for days or even months and, in severe cases, may require hospitalization. Even dried specimens of the plant can retain their stinging properties for years.
11. Chinaberry Tree (Melia azedarach)
The Chinaberry tree, native to Asia and Australia, has been introduced to many other parts of the world as an ornamental plant.
However, all parts of the tree, especially the fruit and bark, contain toxic compounds that can cause severe digestive issues, breathing difficulties, and potentially fatal neurological problems.
This tree has also been used in traditional medicine to treat a range of conditions, including skin diseases and intestinal worms.
The tree’s wood is also valued for its insect-repelling properties and is often used to make furniture and musical instruments.
12. Physic Nut (Jatropha curcas)
The physic nut, a small tree native to Central America, contains toxic compounds called phorbol esters in its seeds, leaves, and bark. Ingesting these toxins can cause severe digestive issues, dehydration, and potentially fatal organ damage.
The physic nut has been used in traditional medicine as a purgative and to treat skin diseases. The plant’s oil is also being explored as a potential source of biodiesel fuel.
13. Poison Sumac (Toxicodendron vernix)
Poison sumac, a shrub or small tree native to eastern North America, contains a potent allergen called urushiol in all parts of the plant. Contact with poison sumac can cause severe allergic reactions, including painful rashes, blisters, and swelling.
Unlike its relatives, poison ivy and poison oak, poison sumac is relatively rare and often grows in wetland habitats. The plant’s toxicity has led to its use as a natural deterrent against herbivores in some agricultural settings.
14. Eucalyptus Tree (Eucalyptus spp.)
While eucalyptus trees are not inherently toxic to humans, they can pose a significant fire hazard due to their oil-rich leaves and bark.
Eucalyptus oil is highly flammable, and the trees have been known to explode during wildfires, contributing to the rapid spread of flames.
In addition to their fire risk, some species of eucalyptus can cause allergic reactions in sensitive individuals. The trees’ pollen, leaves, and bark can trigger symptoms such as runny nose, itchy eyes, and skin rashes.
While trees are generally beneficial to our environment and well-being, it is essential to be aware of the potential dangers posed by some species. These 14 trees serve as a reminder that nature can be both beautiful and deadly.
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Nancy has been a plant person from an early age. That interest blossomed into a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Nancy worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.