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The Most Toxic Garden Plants in the United States

Common Toxic Garden Plants

Poisonous plants might affect different people in different ways – such as with the poison ivy example above. Other reactions poisonous plants might cause include dermatitis, skin photosensitization, internal poisoning, and irritation of internal organs. Depending on the plant, one or more parts could cause a reaction, including pollen, spores, sap, berries, leaves, flowers, seeds, and roots.

Vegetable Garden Plants

You would think that anything grown in the garden would be safe, but the rhubarb plant puts that to rest. While you can eat the stalks, the leaves are fatal. Cooked or raw, the leaves of the rhubarb plant can cause convulsions, coma, and rapid death.

Flower Garden Plants

Many beautiful plants in your garden could cause digestive upset, vomiting, irregular heartbeat, and death. While humans generally do not reach down and grab a handful for a snack, these plants could affect your pets.

  • Larkspur: The seeds and the young plant could cause nervous excitement, depression, digestive upset, or even fatalities.
  • Monkshood: The fleshy part of the roots could cause nervous excitement and digestive upset.
  • Star of Bethlehem: The bulbs of this plant, also known as autumn crocus, could cause nervous excitement and vomiting.
  • Lily-of-the-Valley: This common garden plant's leaves and flowers could cause an irregular heartbeat. You could also experience mental confusion and digestive upset.
  • Iris: The part of the stems that are underground could cause severe digestive upset, though it is not usually serious.
  • Foxglove: The leaves of this plant could cause an irregular heartbeat, especially if taken in large amounts. Foxglove could also cause mental confusion, digestive upset and could be fatal.
  • Bleeding Heart: The roots and the foliage of this common garden plant is fatal to cattle. As for humans, it could be poisonous if taken in large amounts.
  • Hydrangeas: All parts of a hydrangea plant are poisonous. The plant produces cyanogenic glycoside, which could cause vomiting, diarrhea, and depression.

Trees and Shrubs

Not many trees are truly poisonous to humans; however, there are a few. The twigs and foliage of wild and cultivated cherries are fatal. Several trees, including wild and chokeberry, apple, peach, and elderberry trees, produce sugars when the foliage and twigs are eaten. Those sugars contain a cyanide ion, which causes the sugars to turn into prussic acid, also known as hydrogen cyanide. Any trees stressed by drought or frost, damaged by a storm, or chewed on produce more prussic acid than the body can handle. Everything on these trees is poisonous except the fruit. The pits and seeds inside the fruit are also toxic.

The foliage and acorns from oak trees are also poisonous. The poison will eventually affect your kidneys, though it takes a large amount over several days or weeks to cause damage.

Elderberry trees, except for the ripe fruit, are also poisonous. Even using the pithy stems for blowguns can cause digestive upset and nausea.

Finally, the bark, foliage, and sprouts of the black locust are poisonous and can cause weakness, depression, and nausea.


You often find ornamentals in gardens and inside your home as house plants. Some common ornamentals could cause anything from mild digestive upset to death. Common ornamentals include:

  • Laurel, rhododendron, and azalea: Every part of these plants is fatal. They cause nausea, vomiting, depression, difficulty breathing, coma, and death.
  • Lantana Camara: The green berries of the lantana plant, also known as red sage, are fatal. They affect the kidneys, lungs, heart, and nervous system. This plant grows in the southern part of the United States and has moderate climates.
  • Daphne: The berries of this plant are fatal. Just a few berries could kill a child.
  • Jasmine: The berries cause digestive disturbance and nervous symptoms and are ultimately fatal.
  • Wisteria: The seeds and pods could cause digestive upset, which could range from mild to severe. Children are commonly poisoned by wisteria.
  • Yew: The foliage and berries of the yew plant are fatal, though the foliage is more toxic than the berries. Often, those who eat it do not have the warning symptoms before dying.
  • Golden chain: The seeds are in bean-like capsules – it is the capsules that cause staggering, excitement, convulsions, and even coma. The capsules could be fatal.

If you have any of these plants or other poisonous plants in your home or garden, keep them out of reach of children and pets. If you have young children, it is best not to plant these. If you have the plants and have children old enough to play outside, you might consider fencing off that part of the landscaping or removing the plants until the children are old enough to understand that they shouldn't put any plant in their mouths.