Spring is just around the corner and those mopey plants that bore the brunt of winter are gearing up for another year of beautiful blooms. Unfortunately, not all beautiful blooms are created equal. Some incredibly attractive plants can cause everything from headaches to illness or death, leaving children six and under, and our pets, most vulnerable to these deadly plants’ harmful effects. To shield you, your children, and your pets from potential harm, we have compiled a most toxic plants list that could pop up in your very own backyard across North America.
Daffodils, jonquils (Narcissus spp.) – Often mistaken for onions before blooming because of their bulbs, these cheerful yellow and white blossoms can be toxic if you eat enough of them. The yellow-trumpeted daffodil carries two toxic agents in its stems, leaves, flowers, and bulb. The bulb, leaves, and stems of the daffodil contain lycorine, which can be toxic to both humans and pets. Lycorine is a phenanthridine alkaloid found in many flowering plants, such as the amaryllis. All parts of the bulb are toxic to people and animals, but the toxicity level is low unless you eat a large amount. If you ingest lycorine, you may experience diarrhea, nausea, vomiting, abdominal pain, salivating, trembling, depression, convulsions, and tremors. Lycorine is also especially poisonous to cats, dogs, and horses. Symptoms are similar to humans but may also include low blood pressure and cardiac arrhythmias.
The leaves and stems of the daffodil contain calcium oxalate crystals. When the leaves or stems are ingested, the crystals cause immediate pain in your mouth or a burning sensation on your skin and you may experience symptoms including difficulty swallowing, swelling and temporary hoarseness. To avoid what is commonly called “lily rash,” wear gloves and wash your hands if you come in contact with these toxic plants.
Azaleas, rhododendrons (Rhododendron spp.) – The toxic component of rhododendrons and azaleas can be found in very high concentrations in honey made by bees that feed on them. The poisonous honey is commonly referred to as “mad honey“. Ingesting “mad honey” is not the only way to be poisoned by azaleas and rhododendrons. Eating the leaves, nectar, or flowers of the plants can also lead to toxicity. The toxin can cause very low blood pressure, low heart rate, and irregular heart rhythm. Although rare, serious, and life-threatening toxicity has occurred when people intentionally ate the plant. However, there are some areas of the world where the plant is believed to have medicinal value. Generally, only mild symptoms such as mouth irritation, nausea, and vomiting are experienced when children mistake them for honeysuckles. For this reason, it is important to keep a close eye on children (and pets) when they play outdoors to be sure they do not eat any flowers, leaves, fruits, or seeds. If azaleas or rhododendrons are kept indoors, be sure to keep them out of reach of children and pets.
Chrysanthemum (Chrysanthemum spp.) – You may be asking are chrysanthemums poisonous? The answer is yes, all parts of chrysanthemum plants are potentially toxic to dogs, cats, horses, and other mammals. Chrysanthemums have been known for their toxicity for thousands of years. In 100 A.D. their pesticide potential was noted in a Chinese pharmacopeia. In the 1800s the Persians passed on the secret of chrysanthemum powder to Europeans who later exported it to the U.S. Nowadays, few chrysanthemum species are specifically grown commercially for the purpose of making the pesticide, pyrethrum. Although pyrethrum comes from a botanical source, it is highly toxic, killing both beneficial insects and pests-killing a broad spectrum of insects, including beetles, aphids, and caterpillars. How an animal will react to its toxin varies on the animal, its size, the amount consumed, and the chrysanthemum species. Though rarely fatal, chrysanthemums can cause some miserable symptoms if eaten, such as inducing vomiting, diarrhea, stomach pain, excessive salivating, rashes, or a lack of coordination.
Lily of the valley (Convallaria spp.) – Toxicity is this plant’s defense against animals eating its seeds. All parts of the lily of the valley are extremely poisonous when ingested—the stems, the leaves, the small white flowers, and the berries—and close to 40 different cardiac glycosides have been found in the plant so far. Glycosides are chemical compounds where sugar is bound to a non-carbohydrate molecule. By increasing calcium stored in and around cells, cardiac glycosides increase the force with which the heart contracts and the volume of blood it can pump. While this may sound less than attractive, there are current drugs derived from purified cyanogenic glycoside extracted from the foxglove plant in the market to treat arrhythmia and congestive heart failure. In quantities over the recommended safe dosage, though, cardiac glycosides can wreak havoc on your gastrointestinal, circulatory, and nervous systems. Accidental ingestion of lily of the valley can cause symptoms including blurry vision, difficulty breathing, diarrhea, vomiting and nausea, disorientation, drowsiness, headaches, red skin rashes, excessive salivation, sudden alterations in your cardiac rhythm, and possible death.
Hydrangea (Hydrangea spp.) – These beautiful, fluffy blooms, beloved for their showy flowers, have a dark side. Are hydrangeas poisonous to humans or dogs? Several parts of the plant — the buds, flowers, and leaves — contain a compound known as glycoside amygdalin. It’s the amygdalin that has the potential to make hydrangea poisonous to dogs because it can break down to produce cyanide. For hydrangea toxic poisoning to occur, a person or pet must eat very large quantities. Interestingly enough, some individuals harvest hydrangea flowers to dry and smoke for a cheap high. Dried hydrangea plants produce effects similar to symptoms produced by tetrahydrocannabinol (THC), which is found in cannabis plants. The reason hydrangea flowers produce a euphoric feeling is because the amygdalin compound breaks down to produce cyanide-type effects in the cells in the body. Effectively, the cyanide deprives cells of oxygen. Most often hydrangea smokers report effects of dizziness, heart rate increases, and euphoria, but if they smoke enough, the results can include intestinal and respiratory distress. It’s important to realize, though, that hydrogen cyanide is also present in cigarettes, so the potential to poison yourself with hydrangea, while present, is unlikely. Hydrangea poisoning produces severe gastroenteritis symptoms, along with bloody diarrhea, which is frequently bloody, as well as a hydrangea rash or skin irritation. However, most experts agree that the amount of the plant that would have to be consumed would be very large. Nonetheless, keep an eye on pets and small children around hydrangeas.
Houseplants – several common houseplants can be toxic to cats, dogs, and children. These toxic house plants include pothos, peace lily, caladium, oleander(extremely toxic!), philodendron, dieffenbachia, English ivy, and snake plant. There are many, many more but these are just a few of the most common ones. Always do your research before bringing a new indoor plant near your children or pets. Toxicity can happen from ingesting the leaves, stems, or roots of these plants.
It’s always better to be safe than sorry! Be sure to educate yourself and others on some of the harmful effects of coming into contact with the plants or ingesting any of these and other toxic plants potentially growing in your garden or vicinity! If you do come into contact, even a small amount, please contact your local poison control center and tell them about the poisonous plant.