In a well-planted suburban yard many flowering and fruiting plants provide color, form, and texture as well as food for us and our wildlife friends. However, lurking among these lovelies are plants that can be toxic.
In fact, a few of our favorite fruit trees have leaves, twigs, and seeds that are poisonous if eaten. While some flora can cause skin irritation upon contact, others produce allergens that can cause respiratory distress.
As we move toward sustainability, we must be proactive in identifying and learning about all of the plants in our yards. We should also strive to educate our children about which plants can be eaten and those that are potentially harmful. My mother used to say, “Don’t forage unless you know exactly what you are putting in your mouth.” That is a good rule to live by.
The 10 common landscape plants covered here range in toxicity from somewhat toxic to deadly and represent only a few of the scores of potentially harmful vegetation. If you have small children or pets that frequent your yard, it would be best to not add potentially toxic plants to your landscape.
Although very rare, if poisoning does occur, seek medical attention immediately. Be sure to bring along a sample of the plant that was ingested. Also be prepared to give the name of the plant (if possible), as well as how long ago it was eaten; how much and which parts were eaten; the age of the individual and his/her symptoms.
Ten Potentially Hazardous Landscape Plants
These colorful perennial bulbs naturalize readily and bloom in early spring each year. They are also deer and rodent resistant.
Toxic Parts: The entire plant (but especially the bulb) contains toxic alkaloids.
Symptoms: Care should be taken when handling narcissus because contact with the sap can cause skin irritation. Ingestion causes severe gastric distress, but recovery usually occurs in a few hours. Consuming large amounts may cause trembling, convulsions, and even death.
This attractive plant with flowers in shades of gold, orange, pink, and red is planted in containers, hanging baskets, and butterfly gardens.
Toxic Parts: The green, unripe fruit, which contains lantadene A, is highly toxic. The ripe berries seem to be safe and are eaten by wildlife.
Symptoms: Consuming green berries will result in severe digestive distress, difficulty walking, and vision problems. In severe cases, circulatory collapse and death may occur.
Oleander (Nerium oleander)
Oleander is planted in the landscape for its beautiful flowers and drought tolerance.
Toxic Parts: All parts of the plant are highly toxic and potentially fatal, including the flowers and nectar. Smoke from burning the plant can also be harmful. Eating one leaf can be lethal for humans.
Symptoms: Severe digestive disorders, slowed pulse, irregular heartbeat, dilated pupils, coma, and sometimes respiratory paralysis and death.
Azaleas (Rhododendron spp.)
Native and imported rhododendrons are hardy shrubs with colorful, fragrant spring flowers making them good foundation plants.
Toxic Parts: The leaves, flowers, and nectar contain poisonous grayanotoxins.
Symptoms: Consuming azalea leaves can cause burning of the mouth, salivation, watery eyes, and runny nose, which may be followed by severe digestive distress, very low blood pressure, irregular heartbeat and paralysis, but is rarely fatal to humans.
Castor (Ricinus communis)
It is grown as an ornamental for its striking foliage and rapid growth. In the South it is also grown commercially as a source of castor oil, which is used medically and in industry.
Toxic Parts: The deadly poison ricin is concentrated in the seeds, but lesser amounts are also found in the leaves. The FBI classifies ricin as the third most poisonous substance known. The poison is released when the seed’s hard skin is broken.
Symptoms:Poisoning can occur through either contact or ingestion of broken seeds resulting in severe gastric distress, rapid heartbeat, convulsions, and hemorrhaging. Death from kidney failure may occur up to 12 days after eating the seeds.
Morning glory (Ipomoea violacea and I. tricolor)
The heart-shaped leaves and colorful flowers of the fast-growing vines brighten up trellises, fences, and arbors and attract butterflies and other pollinators.
Toxic Parts: The seeds, which contain amides of lysergic acid (similar to LSD, but not as strong), are hallucinogenic and potentially dangerous, but not fatal.
Symptoms: Eating the seeds can cause nausea and hallucinations.
Foxglove (Digitalis purpurea)
Digitalis is cultivated as a medicinal plant for treatment of the heart and also as a cool-weather ornamental for its tall spires of purple to white flowers.
Toxic Parts: The entire plant contains potent glycosides (digitalis) that affect the heart muscle.
Symptoms: Overdose can cause pain in the mouth and throat, gastric distress, severe headache, irregular heartbeat and pulse, tremors, and in severe cases, convulsions and death due to cardiac arrest.
Cherries and Plums (Prunus spp.)
All members of the Prunus genus have attractive flowers, tasty fruit, and colorful fall leaves.
Toxic Parts: The leaves, twigs, bark, and seeds (also called stones or pits) contain a cyanide-producing compound called amygdalin.
Symptoms: Consuming the toxic parts can cause anxiety, confusion, dizziness, headache, vomiting, and pulmonary distress. In severe cases convulsions, coma, and death may occur minutes after large doses.
Yew (Taxus spp.)
These evergreen needled trees or shrubs with pollen cones (male) and reddish berry-like fruits (female) are used as ornamentals because they lend themselves well to pruning.
Toxic Parts: All parts except the red fleshy aril around the seeds contain derivatives of taxane, including Taxol, which is used in chemotherapy cancer treatment.
Symptoms: Ingesting the plant can result in digestive distress, abdominal pain, irregular heartbeat, dilated pupils, collapse, coma, and convulsions. Fatalities may occur when large amounts are eaten or when the seeds in the fruit are chewed and swallowed.
Trumpet Vine (Campsis radicans)
The flowers of this fast-growing native vine attract hummingbirds and butterflies.
Toxic Parts: Contact with the leaves and flowers can cause skin irritation. All parts, except the fruit, are slightly toxic if ingested.
Symptoms: Consuming the plant can cause gastric irritation and dilated pupils. Contact causes skin redness, swelling, and numbness in the hands.
A version of this article appeared in a Jan/Feb 2016 State-by-State Gardening print edition. Photography courtesy of Yvonne L. Bordelon.