By Dr. Mercola
The 12-acre Alnwick Garden in northern England is home to fragrant rose bushes, manicured hedges, a cherry orchard and stunning water features — all things you'd expect in a traditional English garden. But behind a locked gate is a garden with a much more sinister air — a poison garden home to plants that have the ability to kill.
A sign on the gate reads, "These plants can kill," and visitors may only enter with a guide, in groups of 20 or less, who are warned not to touch, sniff or venture too close to the deadly plants. Some are so dangerous they're grown in metal cages with cameras tracking them 24/7. The project was started in 2005 by Jane Percy, the Duchess of Northumberland. Centuries ago, apothecary gardens were quite common in England and were used to grow medicinal plants used for a variety of treatments.
Percy was intrigued by the more macabre side of the plant world, however, explaining to Australia's News.com, "What's really interesting is to know how a plant kills you, and how the patient dies, and what you feel like before you die … Most plants that kill are quite interesting."1
Plants That Can Kill in the Poison Garden
More than 100 deadly plant species can be found in Alnwick's poison garden. The poisonous properties are often used by the plants as a form of protection. Many of them may be harnessed for good (for instance in the treatment of cancer or nerve pain), with the difference between benefit and harm coming in the dose.
For instance, the Helleborus genus of flowering perennials grown in the poison garden were once used to help children get rid of intestinal worms, but if too much was given, it were deadly.2 Other poisonous plants in the garden range from common daffodil bulbs and laurel hedges, for which Percy obtained a special permit to grow. NPR expanded on some of the garden's highlights:3
" … [I]t doesn't take many berries from Atropa belladonna (deadly nightshade) to kill … the plant is common in England and growing happily in the Poison Garden. The duchess also warns that that merely brushing up against the bushy green Ruta graveolens (commonly called Rue) or touching the sap from Euphorbia (the Dr. Suess-like plants sometimes called spurge) can give a person a nasty rash."
Another intriguing plant in the garden is datura, also known as angel's trumpets, a night-blooming perennial and member of the nightshade family. Most part of the plant contain hallucinogens that can cause delirious behavior and death.4 Percy told The Telegraph:5
"Datura is an incredible poison, but an amazing aphrodisiac, too, and you see it everywhere. In Argentina, even nowadays, some people put a bell of Datura … on a baby's pillow at night, then take it away after five minutes and the baby has gone to sleep. If it were left all night the baby would be dead in the morning.
Victorian ladies used to sit around a table with a datura plant in the middle and play cards or have tea. They'd pop their cup under a bell, tap it, and pollen would fall into the cup. They would experience similar effects to that of LSD."
15 More Plants That Can Kill
If you look around your backyard and possibly even your kitchen, you may find a surprising number of toxic plants, ranging from mildly poisonous to deadly. Among them:6
1. Apple Trees
Apple seeds contain amygdalin, a plant compound known as a cyanogenic glycoside. When apple seeds are chewed or crushed and metabolized, the amygdalin turns into hydrogen cyanide, which is poisonous. That being said, the cyanide is produced only if the seeds are damaged (i.e., crushed or chewed), so swallowing a few seeds whole is virtually harmless.
2. Nightshade Plants
The Solanaceae family of vegetables, informally known as nightshades, includes tobacco, tomatoes, peppers, eggplants and potatoes. Some of these plants are of course quite safe and even nutritious for most people, but others may not tolerate them very well.
3. Rosary Pea
This plant goes by many names, including precatory bean, Buddhist rosary bead, love bean, lucky bean, Indian licorice, prayer bean and weather plant. Rosary peas are used as ornamental beads for jewelry around the world, but they contain toxic compounds called abrin (a relative of extremely toxic ricin) and abric acid. It's said that jewelry makers have died after from pricking a finger and handling the peas.7
Consuming even one rosary pea can be deadly to pets, but fortunately the seed's hard outer coat must be damaged (crushed or cut open) to cause harm. So in many cases ingesting the seeds may lead to only mild illness. However, if a broken pea is ingested, it can lead to severe vomiting and diarrhea (sometimes bloody), tremors, high heart rate, shock, fever and death among dogs, cats and horses.
Oleander, or rose bay, contains cardiac glycosides that can cause vomiting, dizziness and cardiac dysrhythmias. In Sri Lanka, yellow oleander seeds are often used as a suicide agent, with thousands of cases reported each year. About 10 percent of cases of oleander poisoning in Sri Lanka are fatal.8
Your pet may also be poisoned from access to pruned or fallen oleander branches while horses may be poisoned by consuming this ornamental plant near horse show arenas.
5. European Yew
Yew contains toxic taxine in its bark, leaves and seeds, which, if consumed, can lead to sudden death from heart failure. Yew leaves and seeds are also sometimes used by people attempting to commit suicide. Keep an eye out on your dogs if you have yew in your yard; even playing with the branches or sticks from the yew tree could be potentially deadly to dogs.
Also known as narcissus, daffodils contain lycorine, particularly in the bulbs. This toxic chemical can lead to nausea and vomiting followed by low blood pressure and liver damage.
7. Doll's Eye
This plant, also known as white baneberry, is a member of the buttercup family. It has distinctive white berries with an eye-like black dot in the center, growing on red stalks. The berries are particularly poisonous, as they contain cardiogenic toxins. It's said that eating five or six of the berries can make you sick while consuming more can be deadly.9
All parts of the hemlock plant are poisonous, but the root contains the greatest concentration of poison. Hemlock is said to have been used to execute Socrates, and there are reports of children dying after making whistles out of hollow hemlock stems.10 Ingesting the plant may lead to muscle weakness and paralysis, progressing into respiratory failure.
9. Stinging Tree
Found in Australian and Indonesian forests, this stinging nettle can lead to a stinging sensation that lasts for weeks. In animals, brushing past the plant may cause a severe allergic reaction.
10. Castor Beans
Castor beans contain the extremely toxic substance ricin. Consuming even one castor bean can kill a human or pet, but the plants are relatively common, even in public areas. Ricin inhibits protein synthesis, leading to convulsions and kidney failure.11 According to NPR:12
"In 1978 a member of the Bulgarian secret police used an umbrella tip to inject ricin — a powerful poison extracted from the beans of a castor plant — into the leg of a political dissident, as he walked down a London street."
This plant, also known as devil's helmet and aconitum, is so deadly that a U.K. gardener died in 2014 after handling the plant.13 It was also a well-known poison in ancient times, used during battles to poison enemies' water.14
12. White Snakeroot
This plant contains toxic tremetol, which is poisonous if ingested, either directly or via contaminated meat or milk. If a cow grazes on the plant, for instance, its meat and milk will become poisonous. Nancy Hanks, Abraham Lincoln's mother, reportedly died from "milk sickness" after consuming milk contaminated with white snakeroot.15
Larkspur contains compounds called diterpene alkaloids that are toxic to humans, dogs, cats and horses. It's thought the toxicity of this plant varies depending on the conditions in which it's grown and becomes less toxic as it matures. If consumed, larkspur can cause neuromuscular paralysis and symptoms such as muscle tremors, stiffness, weakness, convulsions, heart failure and death from respiratory paralysis.
This plant grows striking bell-shaped flowers, but all parts of the plant contain digitalis glycosides, which can affect heart function, leading to irregular heartbeat and death in humans and pets.
15. Melia Azedarach
This flowering tree, also known as white cedar, is native to Australia and contains berries with neurotoxic poisons. Consuming just six berries may be enough to kill a person, but birds are not affected, so they feast on the berries regularly.16
Plant Poisonings Are Relatively Common in the US
While pharmaceuticals remain a top cause of calls to poison control centers, plant exposures also have a top spot on the list. Data from the American Association of Poison Control Centers' National Poison Data System (NPDS) 2013 annual report revealed more than 46,000 plant exposures in the U.S., with more than 29,000 involving children aged 5 years or younger.17
Three deaths were also reported. To avoid poisonous plants, be very careful when selecting which plants to put in your garden or home, especially if you have young children or pets. If you're planning to forage for wild edible plants, consume only those you are sure you can correctly identify and are not poisonous.
Fortunately, there are far more edible plants than poisonous ones. Wild plant enthusiast Sergei Boutenko claims there are thousands of safe, edible plants growing wild in North America, but there are only 150 listed by the American Association of Poison Control as poisonous.18
Of those 150, only about 50 are considered to be "highly poisonous" (i.e., can be fatal), and the rest are classified as "mildly poisonous," which means they may cause nausea, diarrhea or headache, but probably will not kill you. If you see a wild plant you can't identify, the characteristics that you should regard as "red flags" for toxicity include the following. As always, if you're not sure, don't eat it.
✓ Milky or discolored sap
✓ Beans, bulbs or seeds in pods
✓ Bitter or soapy taste
✓ Spines, fine hairs or thorns
✓ Dill, carrot, parsnip or parsley-like foliage
✓ "Almond" scent in woody parts or leaves
✓ Grain heads with pink, purple or black spurs
✓ Three-leaved growth pattern