Pick your poison – the deadliest plants on the planet
From a sting, so painful it drives victims to suicide, to the leaves responsible for 8 million deaths every year, learn about the world’s most horrible herbage and frightening fungi
Cereal killer
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Ergot (Claviceps Purpurea)
In Salem, Massachusetts in 1691, two young girls began experiencing fits and hallucinations and the sensation of being pinched and pricked. The symptoms spread to more young girls, triggering a series of events, which ultimately led to 19 people and two dogs being hung for witchcraft. It was an historical event of mass-hysteria immortalised in Arthur Miller’s play The Crucible. However, scientists and historians now suspect that a fungus may have caused the ‘cursed’ symptoms. Ergot infects cereal grasses – particularly during periods of extended damp – which is then made into bread. People infected with ergotism experience hallucinations, hysteria, and a feeling of crawling on their skin. Records from the Middle Ages report entire villages of people succumbing to ‘dancing mania’, now believed to be the convulsions of ergot infection. Over fifty thousand people are suspected of having died from the condition – sometimes called St Anthony’s fire, owing to the burning sensation felt by sufferers.
Pain worse than death
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Gympie-gympie (Dendrocnide moroides)
‘The most feared tree in Australia’, merely brushing against the gympie-gympie can cause agony for months, if the shock and intensity of the pain does not immediately induce a fatal heart attack. A relative of the nettle, fine silica hairs penetrate the skin, but do not break down, meaning that the toxins inside can be re-triggered by heat, cold or touch for up to a year after the initial sting. The pain is so intense – described as like being simultaneously electrocuted and set on fire – victims have been known to end their lives rather than live with the torture, giving it the grim nickname, ‘the suicide plant’. There is a specimen of the plant at the poison garden at Alnwick, kept in a glass case, so the hairs it sheds cannot be inhaled, or get into eyes. For anyone unlucky enough to touch the plant, there is a treatment - Hydrochloric acid is poured onto the skin to remove the top layer and then wax strips applied and ripped off to take out the hairs. To find out more, listen to the RHS podcast talk to Dean Smith, Guide at Alnwick Poison Garden.
Berry dangerous
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Deadly nightshade (Atropa belladonna)
Every part of this plant is poisonous, but the black berries have lured many to their death, having mistaken them for delicious bilberries. The plant belongs to the Solanaceae family and has many toxic cousins including henbane and mandrake, as well as the tastier: tomatoes, potatoes and chillies. The name belladonna (beautiful woman) is often attributed to the practice of Italian women who dripped tinctures of the plant into their eyes to dilate their pupils and look more attractive. Like many poisonous plants, early doctors used the poison as an anesthetic, and its killer alkaloid atropine continues to be used as an antidote to nerve gas, and to treat exposure to pesticide. The symptoms of deadly nightshade poisoning include rapid heartbeat, hallucinations and seizures. Sufferers are said to be, ‘hot as a hare, blind as a bat, dry as a bone, red as a beet and mad as a hatter.’
Fatal fruit
Suicide tree (Cerbera odollam)
The sweet scent from the delicate white flowers and glossy olive-green leaves hide a dark secret, bite into one of its juicy mango-sized fruits and the toxic flesh will stop the heart beating just a few hours later. The efficacy of this deadly fruit means the Kerala province of India, where the tree grows, has a suicide rate three times higher than the rest of the country. Its easily masked taste and the unremarkable symptoms of vomiting and heart disruption, along with its difficulty to detect in autopsies, makes the plant a popular murder weapon.
Socrates’ farewell
Poison hemlock (Conium maculatum)
Its lacy white umbels have often led to victims making the fatal mistake of confusing hemlock with its innocent cousins, such as parsley, carrot or fennel. Famously, Socrates met his end when, sentenced to death for corrupting the youth of Athens in 399 BC, he chose to drink poison hemlock. Poison hemlock can be found growing in in damp conditions or roadside verges all over the UK, although it is rarer in Scotland and Ireland. The tale-tale signs of hemlock are reddish-purple splotches on the stems and an unpleasant ‘mousy’ odour. Poison hemlock induces a slow muscle paralysis on its victims eventually leading to their suffocation.
Lethal attraction
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Tobacco (Nicotiana tabucum)
Undoubtedly the most deadly plant on the planet, tobacco has managed to enslave humankind into farming it across nearly 10 million acres around the world, despite it killing over 8 million people every year – 1.3 million of whom die from second-hand smoke. The toxic leaves, packed with the alkaloids nicotine and anabasine, can also kill if eaten, and even through prolonged skin contact.
Fortunately, poisoning or harm from plants in a garden environment is rare and any potentially harmful plants that are permitted to be sold should be appropriately labelled.
Read more from thr RHS about potentially harmful plants.
For the latest information see the HTA guide.