Better Safe Than Sorry! – Most Toxic Plants List

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 (Narcissus 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.