How to identify poisonous plants

You’ve probably heard the saying, “Leaves of three, let it be,” as a reminder to stay away from poison ivy. But did you know that that poisonous plants are not just found in the woods or underbrush? In fact, the stems of some of your prettiest and best-producing garden plants could be harmful to your child or pet.

Many of the leaves attached to beautiful blooms, fruits, and veggies that grow in your garden actually may be poisonous if ingested.

Other seemingly harmless plants may cause an allergic reaction or annoying rash if touched.

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Which Plants Are Toxic?

To help you learn how to spot toxic plants in your garden and stay safe as you frolic in nature this season, here are nine tips for poison prevention when gardening this summer!

  1. Young children can choke on berries, stems, and leaves. When you plant your garden and situate your indoor plants, place potentially poisonous or dangerous plants in areas that are out of children’s reach.
  2. Know the plants you are putting in your garden. Are they toxic? The leaves from three very common plants can be harmful — tomatoes, potatoes, and rhubarb.
  3. Do not leave out packs of seeds. Some seeds are poisonous and others may be coated with pesticides that may be harmful to children.
  4. Spray pesticides with caution. If you use them on your plants, wash your hands thoroughly afterward and take care to protect children and pets. The spraying can leave a chemical residue on the skin.
  5. If spraying, only do so on calm days. Always spray downwind away from yourself, others, pets, and homes.
  6. If you spray your lawn, let it dry. Don’t let anyone walk across it until it is dry. Don’t track it into your home on your own shoes.
  7. Keep fertilizers and pesticides in their original containers. Make sure they’re out of the reach of children.
  8. Be careful where you spray. Move children’s toys, play gyms, sandboxes, and bikes out of the spray areas. Remove pet food dishes and bird feeders.
  9. Wear pants, long-sleeves, and gloves when working in unfamiliar areas because poison ivy may be hiding there.



Common Toxic Plants

Following are some common plants that may be toxic to humans and pets, ranging from those that cause severe reactions to those that cause mild reactions.

Severe reactions

Hemlock — The seeds, flowers, leaves, and fruits of the hemlock plant, known as poison hemlock, all are poisonous. They contain poisonous alkaloid chemicals, even a small amount of which can kill you if eaten. The alkaloids slowly poison the nerve-muscle junctions and cause respiratory failure. Even touching this plant may cause a skin rash. There is no antidote for this plant that grows wild throughout the United States and blooms typically during the spring.

Jimson Weed — Teens can abuse these plants and their seed pods for hallucinogenic effects. Side effects include delirium, agitation, elevated heart rate, dry mouth, dilated pupils, blurred vision, and difficulty urinating. Severe toxicity has been associated with coma and seizures, although death is rare.

Night Shade — Deadly nightshade is similar to jimsonweed in severity, while common or black nightshade causes GI upset and is more moderate in toxicity.

Autumn Crocus— The Autumn Crocus resembles a true crocus plant, but actually is a lily. Sometimes confused with wild garlic, it contains a poison called colchicine for which there is no known antidote. The autumn crocus, also known as the meadow saffron or naked lady,  can cause severe gastrointestinal distress, damage to multiple internal organs, and may lead to death without treatment—particularly among children or small animals.

Moderate reactions

American Bittersweet – The berries and bark of some species of this plant contain alkaloids that can cause vomiting and diarrhea in dogs and cats. Large ingestions may cause central nervous system signs, such as weakness or seizures.

Dieffenbachia – Skin exposure to this common houseplant can lead to rash, swelling, redness, and inflammation. Touching the sap and then touching your eye can lead to irritation, corneal abrasion, and, rarely, permanent eye damage. Ingestion or chewing the plant can lead to pain or numbness of the lips and vocal chords.

Acorns — Raw acorns contain a high level of tannic acid, so they can be toxic to humans when eaten in large quantities. Animals can also find acorns to be irritating to the stomach.

Holly Berries – As few as two swallowed holly berries can cause vomiting, diarrhea, dehydration, and drowsiness in children and pets.  Holly leaves also may cause symptoms if eaten but are less alluring to kids because they’re prickly.

Mistletoe — Mistletoe extract can cause inflammation, headache, fever, and chills. A few cases of severe allergic reactions, including anaphylactic shock, have been reported.

Azalea – This plant may cause stomach pain, nausea, vomiting, sweating, diarrhea, lethargy and, in severe cases, problems like labored breathing, convulsions, and coma. Sensitive people may develop contact dermatitis from handling the plants

Daffodil — Although beautiful, daffodils have resulted in severe allergic problems, including death. Symptoms have included allergic rhinoconjunctivitis, asthma, allergic contact dermatitis, irritant contact dermatitis (from contact with narcissus sap), and urticaria (hives).

Yew Berry — Signs of yew poisoning are nonspecific, including nausea, vomiting, impaired color vision, abdominal pain, or muscle spasms. Symptoms include dilated pupils, breathing difficulty, and tachycardia in the earlier phase followed later by bradycardia, convulsions, or unconsciousness.

Jade Plant – Symptoms of skin exposure include itching or burning. Ingesting the plant can lead to considerable signs of an upset stomach.

Poison Ivy, Oak, Sumac — Rash from these poisonous plants is caused by an allergic reaction to an oily resin called urushiol (u-ROO-she-ol). This resin is in the leaves, stems, and roots of poison ivy, poison oak, and poison sumac.

Poinsettia — After touching or inhaling the irritant, some people have a skin rash, while others have wheezing. In severe reactions, more serious problems include chest pain, blood pressure drop, shortness of breath, and wheezing.

Peace Lily — This plant, if eaten, can produce a tingling or burning sensation, followed by swelling of the lips, mouth, and tongue. Sensitive people may get contact dermatitis from touching this plant.

Pepper Plants – Because they are part of the nightshade family, pepper plants contain a group of chemical compounds known as alkaloids. These are toxic chemicals within the plant – in the stems, leaves, unripe fruits or tubers – which protect it from molds and pests. Allergy to these alkaloids is rare, but it can sometimes occur. Most people suffer no ill effects from eating the alkaloids in nightshade foods. Humans consume tiny amounts of these alkaloids relative to body size.

Philodendron — All parts of the plant contain needle-like calcium oxalate crystals which if chewed or eaten can cause immediate pain or a burning sensation and swelling of the lips, mouth, tongue and throat. Swelling may cause copious salivation, difficulty in breathing, swallowing or speakin

Pokeweed — Pokeweed can cause nausea, vomiting, cramping, stomach pain, diarrhea, low blood pressure, urinary incontinence, thirst, and other serious side effects. When it comes into contact with skin, pokeweed may cause irritation and rash.

Schefflera – This common houseplant may cause irritation or intense burning of the mouth, lips, or tongue; excessive drooling; vomiting;  and difficulty swallowing.

Mild reactions

Hedge Apple/Osage Orange — The fruit of this tree is not poisonous, but you probably won’t want to eat it. When you break the fruit of this tree open, it has a milky, bitter sap that eventually turns black. Some people have been known to develop a rash from it. Most animals, except for squirrels, do not find the fruit of this tree to be palatable.

If you or a loved one has eaten or swallowed part of a poisonous plant, please seek immediate medical attention. Visit the Pittsburgh Poison Center website or Emergency Care at UPMC website to learn more about urgent care in critical situations.

Editor's Note: This article was originally published on , and was last reviewed on .

About Pittsburgh Poison Center

The Pittsburgh Poison Center is available 24 hours a day, seven days a week, to provide poison information and respond to emergencies. You can call 1-800-222-1222, 24 hours a day, for emergency help. We answer more than 100,000 calls each year from across Pennsylvania, at no cost to callers. Our staff of nurse specialists has extensive training in clinical toxicology. We also created a network of more than 70 hospitals throughout the state for consultation and follow-up treatment of poison exposure. For nearly 50 years, our symbol Mr. Yuk has helped to educate children and adults about poison prevention and poison center awareness. All stickers of Mr. Yuk carry important poison control phone numbers.