The most deadly and dangerous plants in the world

Around 12,000 years ago in the middle east, a small group of people did something truly remarkable, something that had never been done before, they tilled the land and planted selected crops, these Palaeolithic farmers were the first to put down roots – no pun intended – and we have been cultivating nature ever since. The first gardens followed soon after. The summer people were the first to cultivate plants just because they liked green things. We have had a long time to learn which plants are beautiful and which ones are deadly. Here are 10 plants that have no place in the Garden of Eden but may well show up in your botanical nightmares.

Deadly Nightshade (Atropa belladonna)

This extremely toxic relative of the common Globe tomato has been prized for centuries by alchemists and apothecaries alike, Deadly Nightshade was used by the women of Renaissance Italy in the form of eye drops to make their pupils dilate and lend their eyes an attractive sheen.  The name Belladonna itself comes from the Italian word for beautiful woman, a nod both to the plant’s attractive appearance – lush green leaves and delicate bell-shaped purple and black flowers – and its use in the cosmetics industry.  Belladonna poisoning can cause delirium and harrowing hallucinations as it is absolutely dripping with a naturally occurring chemical called Tropane alkaloids.  These chemicals can have some beneficial effects for a number of conditions, including stomach cramps, diarrhoea, motion sickness, and urinary incontinence, but unregulated ingestion can be fatal if as few as 10 of the invitingly sweet cherry-like berries are swallowed, far less for a child. If ingested, the plant can cause confusion, blurred vision, high blood pressure, rapid heart rate and convulsions. If not treated with physostigmine or atropine, belladonna poisoning can lead to death in as little as 2 hours.

Ingestion of the berries can cause a feeling like flying, leading to a folk myth of it being used as a flying potion in witchcraft. In 1030, Scotland’s King Duncan I, poisoned bottles of wine and handed them over to an army of Danes, which killed them all without his having to draw his sword.         

Nepenthes Monkey Cups (Nepenthes)

The Monkey Cup, also known as Nepenthes, are a type of carnivorous plant that is indigenous to tropical Asia. There are 170 known species of Nepenthes.  Known for their leaves that form pitchers, and deep bowls that are filled with a digestive enzyme that is typically green or red.  Their sweet nectar draws in the prey, and when the insects fall into the pitcher, the sides are too slick to climb up, and they are slowly dissolved over the course of a few hours. Monkey cups are not merely a threat to insects; some specimens have to be large enough to entrap small animals, with the largest species, such as Nepenthes Rajah, having pitchers that can reach up to 40 centimetres (16 inches) in height and holding as much as 3.5 litres of liquid.

The Nepenthes has evolved to have a sophisticated array of ways to attract its prey, from its appearance (which, to an insect, looking at the world through the ultraviolet spectrum – looks very different) to its sweet nectar.  Some have even evolved to smell like rotting meat to attract scavengers and carrion-feeding insects.

The etymology of the name Nepenthe is a reference to Homer’s Odyssey, in which a potion “Nepenthes pharmakon” is given to Helen of Troy by an Egyptian queen to help her forget. The common name – Monkey Cups – comes from a belief that monkeys drank the fluid out of them, in one account, an orangutan, once kept as a pet and later freed, is described as drinking from one of the pitchers with the finesse of a lady drinking tea.

The Gympie-Gympie plant.

Also known as ‘The Stinging Tree’ or ‘The Suicide Shrub’, the Gympie-Gympie plant is native to Australia and parts of Southeast Asia. The Gympie-Gympie plant is well known for having the most painful sting of any plant in the world, it can take months – years even for the incredibly powerful sting to fade.  The sting has been described as like being burned with hot acid and being electrocuted at the same time. The pain can be so bad that it has driven otherwise perfectly healthy adults to suicide. In one account, an officer in the Australian army on manoeuvres went off into the bush to… well, you know.  After a few moments, a gunshot rang out, and the men ran to him and found him dead from a self-inflicted wound, apparently having made the awful mistake of using one of the plant’s large and soft, inviting-looking leaves as toilet paper.

One reason for the sting of the plant being so powerful is partially down to the fiendishly powerful neurotoxin and partly to its delivery mechanism, the leaf surface is covered with thousands of tiny hairs that are extremely fragile and can burrow into the skin and break off at the lightest touch.  If you should have a brush with the plant, the best way to get the stingers out is with a wax hair removal strip.

Irina Vetter, an associate professor at the University of Queensland’s Institute for Molecular Bioscience, christened the new class of neurotoxin mini-proteins found in the plant “gympietides”

The gympietides are quite like spider venom in the way they fold into their 3d molecular structures and target and trigger the same pain receptors. The gympietides permanently change the chemical makeup of the affected sensory neurons.

Bunga Bangkai (Amorphophallus titanium.)

When the local name for the plant – bunga bangkai – literally translates as ‘corpse flower’, you know that it must really, really stink; Amorphophallus titanium is certainly dramatic looking, but this stinky tropical plant is much better experienced from afar. Discovered in the modern world in 1878 by Italian botanist Odoardo Beccari, who was exploring the rainforests of Sumatra in Indonesia.

The Latin name roughly translates to Misshapen giant penis… I think we will stick with the corpse flower.

The titan arum can grow up to 3 meters in height and a meter in width, and its repugnant odour, which has been likened to that of rotting flesh, is actually what entices pollinators to it. The plant pollinates by carrion-eating beetles and flesh flies, attracted by the stench, carrying the pollen to different parts of the flower. Male and female flowers tend to grow on the same plant, with the female ones blooming before the males. This helps keep the flower from self-pollinating since it takes a few days for the males to open up.  Remarkably, the striking flower only blooms for a few days and only opens once every few years; in fact, it only spends 0.01% of its life span in bloom.

The plant is the biggest unbranched inflorescence in the world, reaching over 10 feet tall (a little more than 3 meters) and 1 meter wide. The spathe of the plant is deep green on the outside and dark burgundy red on the inside, with a deeply furrowed texture.

Parts of the flower can be used as remedies for upset stomachs, but would you really want to eat something that smells like that?

Death cap mushroom (Amanita phalloides)

There are approximately 30,000 species of mushroom in the world of which only around 20–25% have been named, and 3% of these are poisonous, and by poisonous I don’t mean give you a bit of a belly ache, I mean will kill you in less than a day if as little as one cap is ingested. Although not poisonous to the touch like the poison fire coral, the death cap mushroom is hands down the deadliest naturally occurring fungus.

Originally found in Europe, thanks to spores hitching a lift in soil and plant samples the death cap mushroom can be found almost everywhere on earth, and looks perfectly innocent; in fact it bares a striking resemblance to straw or Caesar’s mushroom and, unfortunately, taste just as good and there is nothing that you can do to it by way of preparation to lessen the lethal effects. Around 90% of fungus-related poisonings are down to the death cap mushroom.  Should you accidentally eat one of them you will feel like you have a bad bout of the flu, after 12 hours, as the amatoxin takes effect, you will experience intense abdominal pain and bloody diarrhoea this will cause your tissues to dehydrate until your liver and kidneys break down and your central nervous system shuts down with a mortality rate of 50% the deaths cap is one of the most poisonous naturally growing things on the planet.

Over the years, the unassuming-looking fungus has been used in many assassination attempts. Charles VI (Holy Roman Emperor and ruler of the Austrian Habsburg monarchy) is thought to have died after eating a portion of sautéed mushrooms, his death leading to the War of the Austrian Succession (1740 – 1748). Voltaire is quoted as saying, “This plate of mushrooms changed the destiny of Europe.”

Japanese Knotweed. (Reynoutria japonica)

Capable of pushing through 3 to 4 inches (about 10 cm) of solid concrete or tarmac, Reynoutria japonica is one of the most invasive species known to botany. Able to grow 3 to 5 inches (about 12.5 cm) per day, it can reach up to 3m high (approx. 7 meters).  Japanese knotweed is not only a gardener’s nightmare but also a big pain for architects and builders.

In its native Japan, the ecosystem is such that fungi and insects are able to keep it in check; in Europe, there is nothing to stop this bamboo-like weed from running rampant.

One couple lost £250,000 on their property in the UK due to a Reynoutria japonica infestation in 2012.  If Japanese Knotweed should find itself in the foundations of your home, you can either try treating the area with glyphosate or triclopyr – extremely powerful weed killers, although you do need to be mindful of the damage you could be doing to the soil or the water table.  It usually takes at least 3 years to treat Japanese knotweed. Even this isn’t guaranteed to work because there is a good chance it will survive this, the smallest fraction of the root or the plant can lie dormant for up to 20 years.  The only way to be completely sure is to demolish the house, excavate the site down 3-4 meters (10 feet) and start again.

Japanese knotweed is very good at vegetative spread, a small fragment of stem, as long as it contains a node, can re-root and establish itself; for this reason, you should never mow a patch of knot knotweed. In the UK, although it is not illegal to allow the shrub to grow on your own property, it is illegal to allow it to spread, and you might be liable for any damage that it goes on to inflict.

Oleander (Nerium oleander)

The pretty white, pink or red flowers of this tropical to subtropical shrub belie its underlying danger. Also known as the dogbane plant, this poisonous shrub is highly toxic, especially to canines. Ingestion in humans leads to nausea, vomiting, diarrhoea, fever, heart failure and then death.

Oleander is cardiotoxic, meaning that it kills you by causing your heart rate to become erratic by disrupting the electrical signals that control the heart. This can cause any number of problems, including heart block – a condition in which the electrical signals that travel between the atria and ventricles of the heart are blocked – arrhythmia, and cardiac arrest. The Oleander plan causes the heart first to beat too fast, too slowly or irregularly (Arrhythmia) and then stop entirely (Cardiac arrest). Oleandrin, the main toxin found in Oleander, is a fast-acting poison and can start as quickly as only five minutes after ingestion.

Every part of the plant is toxic, even to the extent that the dried leaves or twigs should not be used to make a fire. Although not as lethal as the death cap mushroom, the Oleandrin toxin is very dangerous as little as 100 g (3.5 Oz) being able to kill an adult horse.

Oleander can, in small doses, have therapeutic effects.  The first recorded information about oleander is in the Ebers Papyrus written around 1550bc and was used by Greek and Roman physicians who used the plant as treatment for a variety of conditions, including coughs, diarrhoea, and ulcers. Around 300bc it is thought that small quantities were used recreationally. Theophrastus speaks of a shrub he called onotheras, he describes adding the root to wine, and he said that it “makes the temper gentler and more cheerful”. Given how toxic it is, it’s probably best just to drink more wine and leave the lethal poison out.

Castor Oil Plant.

Ricinus communis, commonly known as the castor oil plant, can be grown almost anywhere in the world. It’s colourful foliage and flowers, and the ease with which you can grow it with make it particularly inviting to gardeners. Despite being the source of Ricin, one of the world’s deadliest poisons, it is perfectly legal to grow. The poison can be extracted using a few household products and a coffee grinder.

Ricin is one of the most perfect natural poisons known to mankind. It is odourless and tasteless and has been used since prehistoric times to assassinate people; there is no antidote, and it leaves almost no trace after killing you. Just three milligrams are enough to kill an adult human; that’s less than a tenth of a teaspoon.

Ricin attaches itself to healthy cells and stops them from making proteins, which means the cells die en masse, which leads to nausea, vomiting, kidney and liver problems and ultimately almost certain death. Symptoms start to show less than 10 hours after ingestion, and there is no known cure. Eating as few as two beans (without being treated) could kill you. Simply swallowing a whole bean (probably) won’t kill you, but chewing the bean, on the other hand, releases the toxin. So, unintentional ricin poisonings are rare.

On September 7^th 1978 Georgie Markov was assassinated by agents of the Bulgarian communist regime (whom he was very critical of) using a poison pellet (just 1.5mm in diameter), hidden inside an umbrella that contained lethal dose of Ricin, he was admitted to the next day and died on September 11^th 1978. The pellet was so tiny it was only found after a postmortem.

There have been a number of attempts made by governments to weaponise this lethal toxin, but so far, it has only proved effective at destruction on a personal level.

Lily of the Valley.

Worn on the 8^th of  May to celebrate the coming of summer by residence of Cornwall in the UK  and prized by florists for bridal bouquets, Lilly of the Valley (also known as May bells, Our Lady’s tears, and Mary’s tears.) was used by Kate Middleton and Princess Grace of Monaco in their wedding arrangements and was a  favourite of Queen Elizabeth II. A favourite flower of Christian Dior, a fragrance simulating lily of the valley was released in 1956.  The master perfumers had to synthesise the scent because no natural aromatic extract can be taken from the delicate flowers. The small white flowers contain cardiac glycosides, which are a group of chemicals that have a number of effects on the heart. They have been used for centuries in folk medicine for everything from Leprosy to Epilepsy, there is no modern medical evidence to back up any of the claims about its restorative qualities, and is in fact highly toxic.

Every part of the plant is potentially lethal because cardiac glycosides interfere with the sodium-potassium pump in the heart cells. This pump is the part that controls the electrical gradient over the cell membrane, which is essential for your heart to beat regularly. if the pump becomes blocked, your heart can’t beat effectively, which leads to cardiac arrest, which is lethal in as many as 30% of Lily of the Valley poisonings.

Typically, symptoms start to manifest within 30 minutes to 2 hours of ingestion, medical assistance should be sought immediately.

Tobacco.

Mankind loves a nice smoke; we have been harvesting tobacco for smoking for a little more than 3000 years, starting in parts of Mexico and North America, where it was used by native tribal people for religious and spiritual ceremonies and later recreationally.  Christopher Columbus was the first European to encounter tobacco smoking in 1492 when he found natives of Hispaniola smoking rolled leaves. he took the habit back to Spain with him, and the habit spread to the rest of Europe. This is partly because the addictive substance in tobacco is Nicotine, which, studies have shown, is at least as addictive as heroin.

Nicotine is a stimulant that has a substantial effect on the brain’s pleasure centre. When nicotine is taken in, it speedily reaches the brain where it binds to receptors that unleash dopamine, a neurotransmitter that has a hand in pleasure and reward. This release of dopamine generates a “high” sensation that can be considerably addictive.

Tobacco has been linked to more than 100 million cases of cancer and premature death over the last 50 years, but that doesn’t stop the industry from being very, very lucrative.  In 2021, the global tobacco industry was worth $849.9 billion, with the industry set to grow by 2.4% from 2022 to 2030, with the demand for tobacco products coming from the developing world and China, with one-third of global sales occurring in China alone. Smoking continues to cause an excess of 7 million deaths per year, making tobacco the most dangerous plant in the world.