Many of our favourite plants are toxic to our pets, this is not new news to most of us BUT it’s shocking just how many of them are planted in our gardens. I learned this when I read an article called Flowers and Pets on the Grower Direct web site.
Well, guess what – there are many plants that can also kill humans, adults and children alike. Some of them so poisonous that it only takes one ingested leaf to kill! So here’s a list of plants you might want to avoid planting in your garden.
Angel Trumpet (Datura innoxia)
Contains toxic alkaloids that have caused poisoning and death in humans and other animals. This plant is occasionally grown as an outdoor ornamental herb because of its spectacular tubular flowers. All parts of this plant are toxic including leaves and seeds. The toxins in this plant are the tropane alkaloids atropine, hyoscine, and hyoscyamine. General symptoms of poisoning are agitation, choreiform movement, coma, drowsiness, hallucination and an elevated temperature.
Belladonna (Atropa Belladonna)
This plant originates from Eurasia and is used as an ornamental plant in flower gardens. All parts are poisonous if ingested but the berries are the most toxic part. The principal toxins are Tropane alkaloids and atropine. Symptoms of poisoning are fever, rapid pulse, dilation of pupils, hot and dry flushed skin, headache, dry mouth, difficulty in swallowing, burning of the throat, hallucinations and convulsions.
Caster Bean (Ricinus communis)
An ornamental herbaceous shrub that is occasionally planted indoors or outdoors as a rapidly growing annual ornamental. The seeds (and to a much lesser extent the leaves) contain ricin, a protein, which is highly toxic in small quantities. Humans as well as cattle, dogs, goats, horses, poultry, rabbits, sheep, and swine have been poisoned after ingesting the seeds. The seed coat must be damaged to allow water to penetrate the seed interior, thus releasing the water-soluble toxin ricin. Most reported cases of animal poisoning have occurred overseas where the seed is used as food and, if improperly treated, has caused illness and death. Humans who ingested the seeds became ill and died.
The toxin has been used for of suicide and assasination. Two to four chewed seeds can cause death in children. DO NOT ALLOW THESE PLANTS TO SET SEEDS!! The ricin content is highest in the seeds, although a small fraction of the toxin is contained in the leaves. Swallowing a seed without chewing prevents the release of the toxin because of the hard seed coat. However, chewing the seed allows release of the water- soluble chemical, and poisoning can occur.
Ricin, a simple protein (a toxalbumin), is one of the most potent naturally occurring substances. Ricin is soluble in water and is therefore not present in extracted oil. Another protein, called ricinus agglutinin (or ricin), causes hemagglutonating activity, coagulation of the red blood cells. Toxicity from this protein disappears after heat treatment, usually as steam. After the oil is extracted, the remaining pomace is used in some countries as animal feed, if properly treated with heat and water.
There is wide variation in sensitivity to the toxin in different species. A lethal dose by injection may be as small as two-millionths of body weight. Because ricin is a protein, antibodies can be produced by immunization, which allows animals to withstand up to 800 times a normal lethal dose. Ricin has been used by secret intelligence services as an assassination weapon. In one case, the Bulgarian secret police used a 1.53 mm metal pellet containing a reservoir for a few hundred millionths of a gram of ricin to kill a Bulgarian broadcaster. The pellet was injected by use of an umbrella, and the man died within 4 days.
Two to four chewed seeds may be enough to cause death in Children. Symptoms of poisoning include abdominal pains, diarrhea, vomiting, nausea, drowsiness, dehydration, incoordination, and hematuria. In cases of acute toxicity, symptoms appear after several hours to a few days, although they can occur quickly. Griffiths et al. (1987) found that ricin causes apoptotic changes: cytoplasmic shrinkage, nuclear condensation, and breakdown of cells into membrane-bound fragments. Large-scale disruption in lymphoid tissues occurs. Death has been accidental or purposeful. Castor bean contains an unknown potent respiratory allergen. Repeated exposure increases sensitivity.
Jimson Weed (Datura Stramonium)
Jimsonweed is named for a case of human poisoning in Jamestown, Va., when soldiers were poisoned by eating the plant in a salad and then suffered delirium and hallucinations. The seeds and leaves are deliberately used to induce intoxication.
Children are attracted by the large flowers and become poisoned after sucking the nectar from the base of flowers or ingesting the seeds. Occurrences of human poisoning are more frequent than livestock poisoning in recent literature reports however animals of all types can be poisoned. The literature mentions poisoning of cattle, goats, horses, poultry, sheep, and swine. Because of the plant”s strong odor and unpleasant taste, animals consume it only when other food is not available. The seeds are sometimes milled with other seeds and have caused problems.
All parts of this plant are poisonous including flowers, leaves, mature fruit, seeds and stems. Several tropane alkaloids including hyoscyamine, hyoscine (also called scopolamine), and traces of atropine are found in the plant. The total alkaloid content in the plant varies from 0.25 to 0.7%. The alkaloids are found even in the nectar and can contaminate honey. Symptoms of poisoning are agitation, babinski reflex, choreiform movement, confusion, convulsions, death, dizziness, drowsiness, faintness, unsteady gait, hallucination , elevated heart rate, inebriation, memory loss, dry mouth, nausea, pupil dilation, reflex excitability, dry skin, flushed skin, slurred speech, elevated temperature, thirsty, unconsciousness, absent urination and impaired vision.
Monkshood (Aconitum napellus)
This is an outdoor ornamental herb. The plant contains poisonous alkaloids, which have proved toxic in humans when accidentally ingested. Few cases of animal poisoning occur. All parts are toxic including leaves and roots. The toxin in this plant is aconitine. General symptoms of poisoning are agitation, faintness, muscle weakness, nausea, salivation, cold and moist skin, throat constriction, tingling sensation and vomiting.
Moonseed (Menispermum canadense)
A native vine found in south-central Canada. In Pennsylvania the fruits of this plant have apparently killed children. The toxic part of this plant is the mature fruit. Moonseed contains alkaloids that may be responsible for the toxicity of the fruit to humans (Lampe and McCann 1985). Acutamine, an alkaloid, has been found in the aboveground part of moonseed, but has not been proved to cause the toxicity. Other alkaloids have also been found in the rhizomes. There are only two symptoms of poisoning, convulsions and death. Gress (1935) describes a case where children ingested moonseed berries and later died. Lampe and McCann (1985) state that convulsions may result when the berries are ingested.
Oleander (Nerium oleander)
An ornamental indoor shrub found in Canadian homes and offices. This plant is quite toxic if the leaves or stems are ingested. Humans have died after eating meat that was skewered with oleander stems. Ingesting a single leaf may be toxic to a person. The dry leaves remain toxic. Cattle, horses, and sheep have been poisoned experimentally. Livestock are not likely to have access to oleander in Canada. Children and family pets should be prevented from ingesting green or dry leaves, chewing stems, or sucking the nectar from flowers. All parts of this plant are toxic including flowers, leaves, stems and young shoots. Oleandrin, a cardiac glycoside, is found throughout the plant, including the nectar of the flowers. Smoke from burning twigs is also said to be toxic.
Humans have been poisoned from using the twigs of oleander to skewer meat or roast frankfurters. Ingesting a single green or dry leaf may cause poisoning. Symptoms include dizziness, abdominal pain, vomiting, unconsciousness, bloody stools, and light and rapid pulse. Death has occurred in some cases. Symptoms occur several hours after ingesting a toxic dose.
Precatory-Pea (Abrus precatorius)
Seeds contain a chemical called abrin, which is highly toxic. A single well-masticated seed can kill an adult human.
In Canada the seeds of this plant are imported into the country on necklaces and perhaps on other decorative items. These attractive seeds are shiny, red, and black and about 5-8 mm long. Seeds are the only toxic part of this plant. The toxin is called Abrin it is a lectin of Abrus precatorius and is a ribosome-inactivating protein. This chemical is regarded as one of the most deadly plant toxins known. General symptoms of poisoning are abdominal pains, red and inflamed cecum, cerebral edema, death, diarrhea, purple gastric mucosa, nausea, gray mucous stomach and vomiting.
Spurge Laurel (Daphne laureola)
An ornamental shrub that is poisonous to animals that ingest it. The Daphne species causes few cases of poisoning, but children or family pets can be affected. All parts are toxic including bark, leaves, flowers and mature fruit. The toxins in this plant are daphnetoxin,
dihydroxycoumarin and mezerein. General symptoms of poisoning are abdominal pains, diarrhea, dysphagia, irritation of mouth, salivation and thirst.
Western Water Hemlock (Cicuta douglasii)
A native perennial plant found in wet soils in British Columbia. This plant is poisonous to all types of livestock and to humans. Many cases of poisoning have occurred in cattle, sheep, and horses. Pigs seem more resistant to the toxins, but they have still been poisoned. Humans have also been poisoned by this plant. Children are especially susceptible because ingestion of only one bite of the rootstock is sufficient to cause death. Adult humans can be poisoned and can die with only two or three bites of the rootstock. The onset of symptoms is so rapid that treatment may not be successful. The toxins are concentrated in the chambered rootstock but also occur in the leaves, stems and young shoots as well. The toxic chemical in this plant is cicutoxin. The only symptom listed is coma followed by death.
Information on the above plants was taken from The Government of Canada.
This final plant is not deadly to humans but kills large insects and small animals. I just couldn’t resist putting it on this post as it’s an extremely unusual looking plant!
Giant Pitcher Plant (Sarracenia spp)
This plant can be found 5000 feet above sea level in the Philippines. This giant carnivorous pitcher plant secretes a sticky nectar-like substance which lures unsuspecting prey into it’s center which contains a pool of enzymes and acid. Sticky, downward ribs makes it almost impossible for trapped creatures to escape. The plant’s diameter is large enough to trap rodents and other small animals, but insects are its most common meal. Pitcher plants, of which there are about 600 different species, tend to grow in nitrogen-deficient environments, and therefore get their nutrients from decaying victims.