13 Plants That Could Kill You - Deadly plants

Over the millennia, people have learned through trial and error which plants are good to eat and which are best to avoid. In our modern, urban world, much of that cultural knowledge has been forgotten. Many gardeners may be surprised to discover that they are growing some of the world's deadliest plants in their own backyards. Here are 13 plants with lethal tendancies. (Text: Bryan Nelson)

Apples: Apple seeds contain cyanogenic glycosides. If you eat enough of the seeds, you could very well die, according to this Mother Nature article.

The real risk is very slight, however, because your body can detoxify small amounts of cyanide, and you'd have to actually chew large amounts of seeds to suffer ill effects. Children and pets are at higher risk than adults.

According to another article on About.com, "symptoms of mild poisoning include headache, dizziness, confusion, anxiety, and vomiting. Larger doses can lead to difficulty breathing, increased blood pressure and heart rate, and kidney failure."

Deadly Nightshade: The nightshade family includes plants such as potatoes, tomatoes, eggplants and chili peppers. While deadly nightshade is the most dangerous, all of these plants contain toxins, usually in their foliage.

The name says it all — both the foliage and the berries of this plant are extremely toxic. Deadly nightshade has a long, colorful history of use as a poison, but what many people don't realize is that the nightshade family includes common food plants, including potatoes, tomatoes, eggplants and chili peppers. In fact, all of these plants contain toxins — usually in their foliage — that can be harmful. In particular, humans and pets should avoid potato and tomato foliage and vines in the garden.

Rosary Pea: Rosary peas are traditionally used as ornamental beads. Many jewelry makers have died after handling rosary peas, which contain abrin, a fatal toxin.

This plant may sound pious, but it's actually deadly. Rosary peas got their name from their traditional use as ornamental beads for rosaries. They are used in jewelry around the world. Many jewelry makers have died after pricking a finger while handling a rosary pea. The poison contained within the seed is abrin — a close relative of ricin and one of the most fatal toxins on Earth.

Oleander: Oleander is a common garden plant, but ingesting any part of it can be deadly. Even the smoke from a burning oleander can kill you.

Oleander is one of the most toxic, commonly grown garden plants in the world — and oddly enough, it's often found in schoolyards. Ingesting any part of this plant can be deadly, especially for children. Even smoke from burning oleander can be fatal. In fact, according to the Toxic Exposure Surveillance System (TESS), there were 847 known human poisonings in the United States related to oleander in 2002.

European Yew: Nearly all parts of this tree are poisonous. The leaves and the seeds contain a poison called taxanes.

Relatively common in Europe, northwest Africa and the Middle East, nearly all parts of this slow-growing tree can be poisonous. The exception is the red fleshy aril that surrounds the toxic seeds. The aril is frequently eaten by birds. Some people have chosen to commit suicide by ingesting the leaves or the seeds, both of which contain a poison called taxanes.

Daffodils: Daffodils are deer- and vermin-resistant, and no wonder -- they have a poisonous numbing effect.

Prized for their beauty, daffodils grow from bulbs that could be mistaken for an edible food, like an onion. Daffodils — also known by their Latin name Narcissus — are common ornamental plants with a bright, cheery and mostly toxin-free flower. Most daffodils are deer- and vermin-resistant, but gardeners shouldn't overlook the dark side of this plant. The Greek philosopher Socrates sometimes referred to daffodils as the "Chaplet of the infernal Gods." because of the plant's numbing effect.

Doll’s Eye: The fruit of a doll's eye plant contain cardiogenic toxins that can lead to cardiac arrest and death.

It's a good thing the creepy-looking berries of this plant aren't enticing, because consuming the fruit of a doll's eye plant (or white baneberry) could kill you. The berries contain cardiogenic toxins that can have an immediate sedative effect on cardiac muscle tissue. Ingestion of the berries can lead to cardiac arrest and death.

Hemlock: All parts of the plant contain the alkaloid coniine, which causes stomach pains, vomiting and progressive paralysis of the central nervous system.

This is one of the most famous poisonous plants in history — it's the flora responsible for killing Socrates. All parts of the plant contain the relatively simple alkaloid coniine which causes stomach pains, vomiting and progressive paralysis of the central nervous system. Hemlock is also known by several common names, including devil's porridge, beaver poison or poison parsley.

Stinging Tree:This plant is the deadliest and most potent stinging nettle in the world. The nettles contain a potent toxin that has been known to kill humans.

Found in forests in Queensland in Australia and Indonesia, Dendrocnide moroides is the deadliest and most potent stinging nettle in the world. Accidentally brushing past any part of this plant can deliver a potent toxin that will cause a painful stinging sensation lasting for days or even months. A severe sting from this plant has been known to kill humans, and it is certainly deadly to pigs, horses, dogs and most other animals.

Castor Beans: One castor bean contains enough ricin to kill an adult within a few minutes.

If you have consumed castor oil before, you might be surprised to learn that castor beans contain one of the most poisonous substances in the world, ricin. Just one castor bean has enough ricin to kill an adult within a few minutes. Despite this grim quality, castor bean plants are frequently grown for decorative purposes.

Angel’s Trumpet: All parts of these plants contain dangerous levels of poison. People sometimes die trying to create recreational drugs from the plant.

Angel's trumpets are woody-stemmed bushes with pendulous flowers that hang like bells. They are prized as decorative additions to the garden because of their elegant flowers. The catch is that all parts of these plants contain dangerous levels of poison and may be fatal if ingested by humans or animals. Angel's trumpets have occasionally been used to create a recreation drug, but the risk of overdose is so high that these uses often have deadly consequences.

Monkshood: Monkshood was used by ancient warriors to poison the water of their enemies.

Monkshood has a long tradition as a deadly plant and was used by ancient warriors to poison the water of their enemies. It was once used as a popular werewolf-detection tool. The flower was held near the alleged wolf’s chin, and if a yellow-tinged shadow appeared, that was confirmation that the person was a werewolf.

White Snakeroot: White snakeroot contains the toxin tremetol. Abraham Lincoln's mother reportedly died after swallowing snakeroot-contaminated milk.

White snakeroot contains the toxin tremetol, which can be poisonous if consumed directly or second-hand. When snakeroot is consumed by cattle, the animals' beef and milk become contaminated with the toxin, and ingesting those substances can lead to a condition called milk sickness. Abraham Lincoln's mother, Nancy Hanks, reportedly died after swallowing snakeroot-contaminated milk. Human disease is uncommon today because of current practices of animal husbandry and the pooling of milk from many producers, but milk sickness does still occur.