Six Common Backyard Plants that Could Kill You

These plants add beauty and interest to your garden, but it’s important to know how to avoid their toxic effects.

June 29, 2009

RODALE NEWS, EMMAUS, PA—For most of us, a backyard garden serves as a sanctuary of beauty and peace. But did you know that, lurking among your beautiful beds, there may be plants whose toxic leaves and berries have been used throughout history to commit murders most foul? In her new book, Wicked Plants: The Weed That Killed Lincoln's Mother and Other Botanical Atrocities (Algonquin Books, 2009) author Amy Stewart tells the compelling tales of “botanical atrocities”—from the drugging of British soldiers with jimsonweed, to the killing of the Greek philosopher Socrates with poison hemlock. And it turns out many of the plants used in these crimes are still commonly cultivated today by many a backyard gardener.

Before you throw down your spade and run from the garden for good, it’s important to know that even the deadliest of plants is usually harmless unless ingested or otherwise mishandled. “I actually don’t think people should be frightened by these poisonous plants,” says Stewart. As she points out, there are plenty of toxic products in our bathrooms and under the kitchen sink, but we’re not afraid of them. The key is to avoid ingesting these substances and keep them out of reach of children and pets. The same precautions should be followed with poisonous plants. “We just have to remember that most of what comes out of the ground was not intended to be food for people.”

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Here six of the most common poisonous plants:

#1: Oleander. One of the most poisonous plants known, this evergreen shrub is commonly grown throughout warmer areas of the U.S. In California, it’s even grown along roadsides and used to decorate highway medians because it’s drought tolerant and deer won't eat it. The showy and often fragrant flowers make this a popular ornamental for backyard landscapes, but care must be used to keep children and animals from eating any part of the plant, as all are poisonous. Ingesting even a small amount of the leaves can be lethal, or cause severe gastrointestinal and cardiac reactions.

Even oleander sap can cause skin irritations, numbness, and eye inflammation if it comes into contact with your hands or skin. If you have kids running around, it might be wise to remove this plant from your yard, as children can be attracted to its bright flowers. Just be sure to wear gloves when pulling it out.

  #2: Castor bean. This popular plant, which is an annual in some areas and a perennial in tropical zones, is grown nationwide. Its multicolored, palmlike leaves and brightly hued, spiny flowers add a tropical punch to landscapes, but the ricin-laced seeds deliver their own pop if ingested. Ricin is known as the most deadly poison the plant world makes; it’s said that eating just one seed can kill a child. The symptoms of poisoning start a few hours after ingestion and include abdominal pain, vomiting, diarrhea, severe dehydration, and, potentially, death. Keeping people and animals safe is as easy as stopping the plant from going to seed; just pinch off the pods as soon as they appear. An even safer option: Don’t grow the plant in or around homes with small children.
#3: Daphne. The sweet, strong fragrance of this evergreen shrub’s flowers (which bloom in shades of green, white, or pink) is a welcome sign of spring in warmer areas of the country. Its berries, however, are extremely poisonous, and caution should be used to keep kids from ever popping them into their mouths. Eating even a handful could be killer. While the unassuming size of the plant makes it popular to grow in containers, you may want to plant it in less easily accessible areas instead if you have kids around, or remove it altogether.
#4: Lantana. This perennial flowering plant is hugely popular in southern states and warmer western states like Texas and California. Aromatic flowers in red, orange, and yellow attract the nose and eye, but don’t let the berries tempt your taste buds: They’re most toxic while still green, before they turn a blackish shade, but even eating the darker berries can make you sick. Keep kids away while the berries are green, or remove the plant altogether until children can be trusted not to snack on the shrub.
#5: Yellow jessamine. Also known as Carolina jessamine—the evergreen vine is the state flower of South Carolina—this plant has trumpet-shaped yellow flowers that may look beautiful but, like every other part of this plant, are also deadly. Unfortunately, children may mistake the flowers for honeysuckle and attempt to drink the nectar found in the buds. Though ingesting the plant would likely just make an adult sick, there have been reported cases of children dying after ingestion. If there are young children in your home, you may want to think twice about planting this decorative vine.
#6: Monkshood. The root of this hardy, ornamental perennial flower with blue or yellow buds can easily be mistaken for horseradish—but with deadly consequences. Ingesting several milligrams of the plant’s poison, which is concentrated in the mature tubers, can kill an adult or cause symptoms such as paralysis, nausea, and vomiting. Never leave the bulbs of this plant lying in your garden to tempt hungry animals and children (or horseradish lovers!). If you plan on removing it from your garden, make sure you wear gloves, as simply picking the plant’s leaves with bare hands can allow the toxin to be absorbed through the skin. You’ll feel some tingling followed by numbness and, potentially, cardiac effects as well.