Top 10 List Of Surprisingly Poisonous Plants

By Marisa Ramiccio. May 7th 2016

We all know that poison ivy and poison oak are toxic and that nightshade and foxglove are highly poisonous plants, but what other plants should we take caution to avoid? It may seem surprising, but many common garden and house plants are poisonous or contain poisonous parts. Not only are these plants toxic to humans, they can also be toxic to dogs, cats and other animals. If you like to garden or decorate your house with plants, be careful when working with these 10 poisonous plants.


Oleander is an evergreen shrub that can have white, red, pink or purple flowers. It also goes by the name of rosebay. This plant is extremely toxic to humans, cattle, dogs, goats and sheep. Oleander contains quite a few poisons including oleandroside, nerioside and saponins. It also contains cardiac glycosides, which can cause irregular heartbeats, convulsions and even death if ingested.


This plant is popular around the Easter holiday, but it’s best kept away from the dining room table. The bulbs contain toxic alkaloids that can cause nausea, vomiting, abdominal pain and tremors, among other reactions. Amaryllis is particularly harmful to dogs and cats, so keep these flowers out of their reach.


This popular springtime flower can actually be toxic if ingested in large quantities and can be particularly harmful to cats, dogs and horses. The bulb of the tulip contains glycosides and alkaloids that can cause nausea, dizziness and abdominal pain. Severe poisoning can lead to convulsions and possibly death. Daffodils and narcissus also contain glycosides and alkaloids and can cause a similar reaction.

Snake Plant

The snake plant is more commonly known as Mother-in-Law’s Tongue, but is also often referred to as dumb cane or dieffenbachia. Like oleander, the entire plant is toxic. It contains saponins and other toxins that can cause the tongue to swell and burn, and can also cause irritation of the mouth. If the tongue swells to the point that the airways are blocked, the results can be fatal. This plant can also cause nausea, vomiting and diarrhea if ingested by dogs or cats.


Lilies are highly toxic to humans, cats, dogs and goats. The leaves and flowers are where the poison is concentrated, and ingestion can lead to kidney damage. Lily-of-the-Valley is especially toxic as it, like oleander, contains cardiac glycosides and saponins. Another toxic lily is the Peace Lily, also known as the Mauna Loa Peace Lily. It contains calcium oxalate crystals, which can cause the tongue to swell and make it difficult to swallow. Wild hyacinth and Star of Bethlehem contain similar poisons and can cause similar reactions.


Often referred to as mums, chrysanthemums are popular springtime flowers and are often a part of Mother’s Day bouquets. But these plants can be very toxic, particularly to cats, dogs and horses and can cause dermatitis in humans. Chrysanthemums can also cause vomiting, diarrhea, nausea, incoordination and hyper-salivation in animals. That’s because chrysanthemums contain toxins such as lactones, pyrethrins and sesquiterpene.


This plant is often found naturally in wooded or wet areas as well as in many gardens. The root of the iris is where the largest concentration of toxins is found. Iris contains rhizomes and pentacylic terpenoids, which can cause vomiting, diarrhea, drooling and lethargy in cats and dogs. This plant is less toxic to humans, but can still cause nausea, vomiting, diarrhea and stomach pain if ingested. It can also cause skin irritation that usually lasts for a few minutes.


This vine-like plant can often be seen growing along the side of the road or alongside a house and blooms in white, blue or violet. The seeds and pods of this plant contain wisterin, which is both a glycoside and a toxic resin. Ingestion in large quantities can cause nausea, vomiting, diarrhea, stomach pain and other digestive problems. Young children often become ill from wisteria, and it can also be harmful to cats, dogs and horses.


Many gardens contain hydrangeas, which grow in clusters of white, pink or blue flowers. The leaves and flower buds of this plant are toxic, particularly to humans, dogs, cats and horses. Hydrangeas contain a cyanogenic glycoside called hydrangin, which can cause nausea, vomiting, and stomach pain when ingested in large quantities.


Azaleas and members of the rhododendron family are quite toxic, particularly to animals. These flowers contain grayanotoxins, which can cause nausea, vomiting and depression of the central nervous system if ingested by animals. Severe poisoning can result in coma or death.

Just because these plants are toxic doesn’t mean you can’t keep them in your garden or on your kitchen windowsill. In fact, some of them can be used as a natural form of pest control. But make sure you keep them out of the reach of curious, young children and pets to protect their health.


More in category

Related Content