Poisonous/Toxic Plants

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There are many common household and outdoor plants that contain compounds that can be toxic (some to the point of death) to humans and animals. Unidentified plants should never be consumed.

If they are accidentally ingested do not give the person anything to eat or drink and call the CT Poison Control Center  at 1-800-222-1222 immediately.

For a listing of plants that are toxic to animals please visit the ASPCA Animal Poison Control site.

Indoor Plants

Common Name   Latin name  Comments
Mistletoe Phoradendron serotinum A common Christmas decoration hung in the home. The white berries are particularly toxic. Causes vomiting, diarrhea, convulsions and coma.
Contains amimes beta-phenylethylamine and tyramine.
Philodendron Philodendron All parts contain needle-like crystals of calcium oxalate, as well as other chemicals. Causes intensely painful burning sensation in the mouth and throat with swelling of the soft tissue area. Vomiting and diarrhea, too. Death from swelling of windpipe.
Caladium  Caladium All parts contain needle-like crystals of calcium oxalate, as well as other chemicals. Intense burning of mouth and throat and swelling of soft tissue. Can block windpipe and cause death. Vomiting and diarrhea also.
Poinsettia Euphorbia pulcherrima All parts contain a milky juice that can cause a rash in some people. Can cause irritation in mouth and throat if eaten. No known toxins. Not as poisonous as its reputation.
Dumb Cane Dieffenbachia All parts are poisonous. Common house plant. Causes severe mouth irritation and swelling if eaten. Contains Calcium oxalate, and toxic proteins.

Outdoor Plants

Common Name    Latin name    Comments
Mushrooms and
Fungii Many types of mushrooms and toadstools are poisonous. You can’t tell just by looking so assume all are toxic. Causes various symptoms from hallucinations, vomiting, diarrhea, pain and death. Contain peptides and alkaloids. Contact the Connecticut Mycological Society for plant identification.
Apple pips Malus sp. Contain small amounts of amygdalin, a sugar and cyanide compound. Extremely large doses can cause adverse reactions.
Azalea, Rhododendron Rhododendron spp All parts are poisonous including flowers. Common landscaping plant. Causes salivation, vomiting, staggering walk, convulsions, difficulty breathing and collapse. Contains Andromedotoxin.
Bloodroot Sanguinaria canadensis Underground stems, roots, and their red contents are poisonous. Causes irritation of the mucous membranes of the mouth, throat, and stomach then intense burning, nausea and vomiting. Toxin is alkaloid, chiefly sanguinarine.
Cherry, Peach Prunus sp. Other than the fruit, all parts are extremely toxic including the leaves, stems, twigs, and pits. They contain cyanide which can lead to difficulty in breathing, dizziness and death.
Deadly Nightshade Atropa belladonna Roots, leaves and seeds are poisonous. Causes drying of the mouth, dilation of pupils, a very rapid heartbeat and central-nervous-system depression. Toxins can be absorbed by handling leaves and eating fruits. Contains atropine, hyoscyamin and scopolamine.
Holly Ilex spp Leaves and berries contain a bitter substance. Berries are attractive to children. Commonly used as a Christmas decoration. Often used as a foundation planting. Causes vomiting and diarrhea and stupor.
Foxglove Digitalis purpurea The leaves and seeds are toxic. Causes nausea, vomiting and dizziness. Can cause heart failure. Contains the digitalis glycosides chiefly digitoxin, a powerful heart stimulant.
Lily-of-the-Valley Convallaria majalis Roots, leaves and fruits contain harmful principles. Causes dizziness and vomiting when large quantities are consumed. Contains the glycoside convallatoxin which stimulates the heart muscle.
Poison Ivy Rhus toxicodendron All parts of the three-leaved plant are poisonous, even the tiny plant hairs and the smoke if burned. Causes severe itching, rash and inflammation of skin. Blisters form then break and liquid exudes from them. Blisters then crusts over and scabs form. Contains the toxin urushiol.
Poison Sumac Toxicodendron vernix All parts of the plants contain the resin urushiol that causes skin and mucous membrane irritation. Inhalation from smoke of a burning plant may cause the rash to appear on the lining of the lungs, extreme pain, and possibly fatal respiratory difficulty. 
Pokeweed Phytolacca Americana All parts are poisonous, particularly roots, shoots and unripe berries. Causes nausea, vomiting, drowsiness and impaired vision. Large amounts can cause coma and death. Toxin is sapon.
Rhubarb Leaves Rheum rhabarbarum The leaves contain oxalic acid which is a nephrotoxic (kidney-related) and corrosive acid.
Tomato and Potato Leaves and Stems Solanaceae family Part of the nightshade family, the leaves and stems contain the toxin glycoalkaloid solanine. The green fruit also contain small amounts of the toxic alkaloid tomatine.
Yew Taxus Canadensis All parts are poisonous. Bright red fruits are on needle bearing evergreen shrub can cause nausea, vomiting diarrhea, abdominal pain, circulatory failure and difficulty breathing. Contains taxine, an alkaloid which depresses heart function.

Revised by UConn Home and Garden Education Center 2016.