Flowers: bright, colourful, fragrant, beautiful. Oh, and don’t forget deadly. 

Poisonous flowers have been wreaking havoc amongst clumsy horticulturists and curious naturalists throughout time. Their seemingly harmless exteriors have led to the accidental deaths of countless animals and humans. 

And let’s not forget those who have exploited the dangerous powers of these poisonous plants throughout history, like Socrates, who chose death by hemlock in 399 BCE.

Toxic plants can blend in amongst the roses and the tulips with ease. So, it might be worth learning exactly what to look out for in that unusual bouquet of colourful flowers your arch nemesis just left on the doorstep.

Here are 8 of the most poisonous flowers in the world to keep you in the know.

Deadly Nightshade

Deadly Nightshade

Also known as belladonna, deadly nightshade is a poisonous flower that you’ve probably already heard of. Despite its innocent looking exterior, this plant, its pretty purple flowers and its juicy black berries, are extremely toxic. When ingested, deadly nightshade can cause blurred vision, loss of balance, headaches, confusion, hallucinations, delirium and then, ultimately, death. 

According to Scottish folklore, in the 11th century, Duncan I’s soldiers poisoned an entire invading Danish army with deadly nightshade, leaving them severly weakened and allowing the Scots to overpower and murder them in their sleep. Keep an eye out for this one. 

Nerium Oleander

Nerium Oleander

They say to never judge a book by its cover. Well, the same goes for flowers. Nerium oleander is an unquestionably beautiful plant, famous for its delicate white or pink flowers.

You’d probably be shocked to discover that this pretty plant actually has one of the most poisonous flowers in the world. If ingested, it can cause vomiting, diarrhea, seizures, coma or even death. Contact with the plant alone can cause skin irritations. 

In fact, the oleander’s toxins are so deadly that people have fallen ill after eating honey made by bees who have visited it. Now that’s toxic. 

Castor Bean

Castor Bean

Found in tropical regions around the world, the castor bean plant (Ricinus communis) is commonly known as the source of the multipurpose castor oil, which is used in food, medication, skincare and other healthcare products. The oil itself is perfectly safe. The plant it comes from, however, is anything but. 


The same seeds that produce the castor oil naturally contain a potent poison called ricin, which can be deadly even in very small amounts. When consumed, it can cause a burning sensation in the mouth and throat, abdominal pain, dehydration, a drop in blood pressure and, within 3-5 days, death. In adults, a lethal dose is just 4-8 seeds.

The castor bean is a truly deadly poisonous flower. 

Poison Hemlock

Poison Hemlock

The clue’s in the name. This is not a plant you want to mess with. Originally found only in Europe and North Africa, this poisonous flower from the carrot family has since made its way across to Asia, Australia and North and South America.

There, it grows rapidly (up to 2.5 metres) and spreads quickly. Its leaves, seeds and roots are dangerously toxic to mammals. Eating just 6-8 leaves is enough to kill an adult human. 

Aconitum

Aconitum 

Known as the Devil’s Helmet, this pretty purple plant can be found in mountainous areas in the Northern Hemisphere. This poisonous flower is deceptively deadly.

Aconitum contains high amounts of the potent toxin acontine, which can cause diarrhea, convulsions, cardiac arrhythmia and death in humans within an hour of consumption. 

Most recently, aconitum was promoted incorrectly as a cure for Covid-19 by the president of Kyrgyzstan, leading 4 unfortunate Kyrgz to end up in A&E.  

Rosary Pea

Rosary Pea

Rosary pea (otherwise known as Abrus precatorius) is native to tropical areas of Asia and Australia. It gets its name from its iconic bright red seeds which are often used in jewellery and prayer rosaries. Sounds harmless, right?

Well, those scarlet seeds are harmless only until their shell is broken. If they are scratched, broken or chewed, their lethal poison (called abrin) is released, causing nausea, vomiting, convulsions, liver failure and death, making Rosary Pea one of the most poisonous flowers in the world. 

Jewellery makers continue to work with the dangerous seeds of the rosary pea, risking illness and death if they accidentally break their shells. 

White snakeroot

White snakeroot

Native to North America, white snakeroot is an innocent looking yet highly poisonous flower found in wooded and weedy areas. It contains a toxin called tremetol, which can cause death amongst cattle if consumed in large amounts.

The poison can also be passed on to humans through the cow’s milk and meat, leading to what became known as ‘milk sickness’. The symptoms of this sickness include loss of appetite, nausea, weakness, abdominal pain and death. 

Before the dangers of white snakeroot were known, thousands of people died of milk sickness in the 19th century. Abraham Lincoln’s mother, Nancy Hanks Lincoln, was one unfortunate victim after she drank the milk of a cow who had consumed white snakeroot. 

Brugmansia

Brugmansia

Brugmansia, commonly known as Angel’s trumpet, is an attractive plant known for its large, trumpet-shaped flowers that can be white, pink, yellow, orange, red or greenish in colour. These iconic flowers can grow up to 20 inches and project a strong, pleasant fragrance that could fool anyone into thinking they are harmless.   

Originally found in South America, all parts of the brugmansia are poisonous, with the seeds and leaves being especially deadly. When ingested, the poisonous flowers can cause hallucinations, delirium, paralysis, confusion, headaches, and tremors. Overconsumption can also result in death. 

And there you have it, 8 of the most poisonous flowers in the world. 

So, next time you’re out camping, foraging, and generally feeling inquisitive about those attractive-looking plants around you, be careful. You never know which deadly poisons exist beneath those pretty petals. 

Who knows, maybe you'll spot one of these flowers on one of our detective day adventures! Find your nearest event here.

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