Plants have many ways of defending themselves – thorns, sharp edged leaves and stings being the most obvious. But some plants take their defences a step further. They contain powerful toxins that can kill. Here are just a few deadly plants that are found in domestic gardens and yet are among the most deadly. So, especially if you have children, take care.

(Before you read this, however, I would like to add a note at the beginning just in case you don’t read to the end. If you suspect that someone has been poisoned by any of these plants GET MEDICAL HELP IMMEDIATELY. Time is of the essence. And it’s better to be safe than sorry.)

Hemlock (conium maculatum)

ThHemlocke poisonous properties of hemlock havebeen known for thousands of years. It is referred to in the Old Testament, and other ancient texts, and is famous for being the instrument by which the Greek philosopher Socrates was executed around 400BC. Hemlock is native to much of Europe and is well established in the United States. It can grow up to 3 metres high. All parts of the plant are poisonous. Its leaves resemble parsley, its seeds are mistaken for anise and its white fleshy taproots appear like parsnips or carrots. It is often, therefore, ingested by mistake but toxins can also be absorbed through the skin.

The toxins in hemlock are known as conium alkaloids and doses exceeding 100mg can be fatal. They work by stimulating the central nervous system causing nausea, headaches, sweating, unsteadiness, salivation and rapid heartbeat. This is followed by drowsiness, depressed heart rate, loss of speech, paralysis and eventual failure of the respiratory system.

There is no known antidote for hemlock poisoning. In the first instance it is important to ensure that the victim’s airway is kept clear. As a temporary measure some advocate giving activated charcoal with water while others suggest tannic acid. (These “treatments” are NOT tested).

Water hemlock is closely related to hemlock and is just as lethal. Symptoms are similar and, again, there is no known antidote.

In the event of suspected hemlock or water hemlock poisoning it is vital to seek urgent medical attention.

Oleander (nerium oleander)

OleanderAlthough deaths from oleander poisoning are uncommon and usually involve direct ingestion, the plant is deemed to be highly dangerous. The leaves, branches and seeds are all toxic.

Oleander is widely grown as a garden plant for its beauty. Historically, it has also been used to treat ulcers, haemorrhoids and leprosy and has also been used to induce abortions.

Oleander contains glycosides. Consumption leads to nausea, reduced appetite, diarrhoea and drowsiness. In severe cases, there may be loss of consciousness, irregular heartbeat and reduced blood pressure. It can lead to breathing difficulties and heart failure. Touching the plant can cause skin irritation. Children are especially at risk; in a tragic incident in 2000 in Los Angeles two young children (aged two and three) died after eating leaves from a neighbour’s hedge.

If you suspect oleander poisoning you must seek medical treatment urgently. Treatment may include the use of activated charcoal and intravenous introduction of fluids to flush the toxins from the system. Doctors may also use a stomach pump to evacuate the system.


Monkshood (aconitum)

monkshoodKnown as the “queen of poisons”, monkshood is just one name for aconitum; other names include wolf’s bane, women’s bane, blue rocket and devil’s helmet. Monkshood is a perennial that grows to about 160cm. Its flowers are very attractive and are most commonly purple to dark blue.

Monkshood is a hardy plant that is favoured by gardeners for use in borders. In ancient Rome, however, cultivation of monkshood was proscribed on pain of death under a decree issued by the emperor Trajan. Why? Because monkshood was a favourite poison of assassins and is possibly still used today, as it leaves virtually no trace.

Monkshood contains the alkaloid toxin known as aconite. Anyone ingesting the poison could die within an hour if they take in enough. Victims can expect a burning sensation inside the mouth and then dizziness, headaches and then vomiting. This is followed by paralysis, convulsions and asphyxiation. Merely touching the plant can cause irritation, dizziness and nausea and the effects are magnified if you have a cut.

There is no antidote but the consensus seems to be that you should induce vomiting and then give powdered charcoal with water. The victim should be kept warm and medical assistance sought urgently.

Belladonna (atropa belladonna)

belladonnaAlso known as deadly nightshade, belladonna is native to Europe, northern Africa and western parts of Asia but is now common in parts of North America. In most places it is considered to be a weed but is sometimes grown by gardeners who like its upright habit and its shiny black berries.

Belladonna (beautiful lady) gets its name from the ancient practice of women in Italy putting drops of belladonna berry juice in their eyes to dilate the pupils to give them a more seductive appearance. It has also been used as a medicine – the Romans used it as an anaesthetic. It is used to relieve colds and hay fever, Parkinson’s disease and motion sickness. It is also applied to the skin to relieve rheumatism, sciatica and even some psychiatric disorders. While its efficacy has not been determined, treatment with belladonna holds risks, as the plant is toxic.

Both the berries and foliage of belladonna contain tropane alkaloids such as atropine, hyoscine and hyoscyamine. Belladonna poisoning induces loss of balance, sensitivity to light, headache, rash, dry mouth and throat, delirium and convulsions. In children, consumption of between two and five berries can be fatal while for adults between 10 and 20 are likely to result in death. Eating just one leaf can prove lethal for both children and adults.

Fortunately, there are antidotes. Physostigmine and pilocarpine are both effective. As with all cases where you suspect poisoning, get medical help immediately.

Daphne (daphne mezerium)

daphneAlso known as the lady laurel or spurge laurel, daphne is a small shrub native to Eurasia but is also widely cultivated in North America. Daphne is well known for the lovely scent of its flowers. However, all parts of the plant are toxic, especially the berries, bark and sap.

Daphne contains two active toxins – mezerein, which takes the form of a resin and can cause skin irritation, and daphnin, a bitter and poisonous glycoside. Chewing a single berry will cause a severe burning sensation in the mouth and throat. Ingestion of a few berries can lead to upset stomach, headaches, delirium and convulsions with death likely to follow if the victim falls into a coma. Fortunately, daphne is very bitter and unpleasant to taste so ingestion is not common.

There is no antidote. If it is on the skin, then washing is all that can be done, while demulcants or an adsorbent like activated charcoal may help if daphne is ingested. In any event, seek medical help immediately.

Stay safe

These are just five of some of the deadly plants you might have in your garden. Make sure that you know which plants are potentially dangerous so that you can keep your family safe from poisoning. And if you do suspect that anyone has ingested part of one of them, then get medical help quickly (and if you can't identify the plant, take some with you so that the medical team can dentify it).