This is an overview of poisonous and non-poisonous plants commonly found in the United States. For each plant on the list we have determined whether the plant is poisonous to humans, dogs, cats, or other livestock. The list is ordered alphabetically.
Usually however, a little more nuance and explanation is required. For instance, some plants are not toxic to humans, but are toxic to dogs, cats or livestock. For that information, please click on the name of the plant which will take you to a more in-depth informative article regarding the toxicity of that particular plant.
– Poisonous Bugs
Poisonous Plants and Berries
Acorns are edible for humans: however, consuming a large number of Acorns without preparing them properly first can cause damage to your liver and increase your risk for certain cancers due to the tannins in the Acorns. All animals should not be allowed to consume Acorns as they are toxic to them.
Angel Trumpet plants have five species and several hybrids, and all are poisonous. They contain hyoscyamine, atropine, and scopolamine in all parts of the plant. They cause tachycardia, paralysis, hallucinations, and death. They affect people, dogs, cats, horses, livestock, and other animals.
Azaleas are poisonous. They can cause health problems in people and animals. Some azaleas in the evergreen family keep their leaves all year around. They contain toxins called grayanotoxins, and they are dangerous to people and animals if they are eaten. Symptoms range from low blood pressure to irregular heart rhythms, mild paralysis, and hallucinations.
Begonias are toxic, containing calcium oxalates and cucurbitacin B. The toxins are concentrated in the tubers, making them the most toxic part of the plant. Begonias are poisonous to people and animals, but there are few incidences of poisoning as the plant produces a burning sensation and is bitter.
The bougainvillea sap is mildly toxic, causing illness if ingested in large quantities. Symptoms include nausea, vomiting, and diarrhea. If a thorn pricks you, you can get dermatitis. Symptoms include itching, pain, stinging, blisters, burning skin, swelling, scaly rash, and sores.
Calla Lilies are poisonous – or rather, toxic – to humans, dogs, cats, and most other animals. This is due to high levels of insoluble calcium oxalate crystals that are small and sharp in nature, causing swelling and pain if they make contact with the sensitive tissues in the body.
Carnations are not poisonous to humans, but they are considered mildly toxic to dogs, cats and other animals.
Chrysanthemums contain pyrethrum, a toxin converted to pyrethrin that has been used as an insecticide for thousands of years. Chrysanthemums also contain sesquiterpene lactones which are highly allergenic. Chrysanthemums are toxic to people and animals and can cause fatal allergic reactions.
Dahlia plants are non-toxic to humans and are used in many different traditional meals across the world. However, Dahlia plants are mildly-toxic to dogs, cats, and other animals. Dahlias can cause many uncomfortable symptoms for your animals, even if your animals do not ingest the plant.
Daffodils contain bioactive alkaloids and calcium oxalate in all parts of the plant. The highest concentration of the poison is in the bulbs. Symptoms include contact dermatitis, nausea, vomiting, diarrhea, and severe abdominal pain. Daffodils are toxic to people, dogs, cats, and horses.
Nippon daisies, poison daisies, English daisies, and oxeye daisies are a few daisy cultivars that are mildly toxic to humans, especially children. Daisies are poisonous to dogs, cats, and horses. Symptoms of poisoning include mild gastrointestinal issues such as nausea, vomiting, and dermatitis.
Dandelions are not poisonous, but they can cause health problems if eaten in large quantities. The stalks of dandelions contain latex, which is rich in beta-lactoglycerol. In addition, the leaves contain oxalates, and eating too much can cause damage to the body. Symptoms might include excessive thirst, vomiting, diarrhea, respiratory issues, and irritation to the mouth, throat, or stomach.
Daylilies are non-toxic to humans, and their flowers are used in many different recipes. However, Daylilies are mildly-toxic to dogs if they are consumed in excess. These plants are highly toxic to cats and livestock animals and horses; they can kill the animal within 24 hours.
Flowering dogwood berries are not classified as poisonous but are considered non-edible. Kousa dogwood berries are considered edible. Flowering dogwoods can give humans rashes and irritate the stomach. Large amounts can give dogs and cats GI distress, such as vomiting and diarrhea.
Elderberries contain lectins and cyanogenic glycosides, which are poisonous to people, cats, dogs, cows, and sheep. The poisons can be deactivated by cooking the berries or flowers for at least forty-five minutes. Elderberries contain vitamin C and antioxidative and anti-inflammatory properties.
Elephant ears are poisonous because they have calcium oxalate, which is also oxalic acid. It is a chemical compound that also exists in Dieffenbachia leaves, and it has sharp crystals in it that can be deadly in larger amounts. That said, when the plant is cooked, the crystals break down. There are different species of the plant as well, and some are more poisonous than others.
Eucalyptus leaves are poisonous to most people and animals. Eucalyptus leaves contain eucalyptol, which is an organic compound that is toxic in higher doses. It is the oil from these leaves that should not be consumed. However, it has several health benefits in very small doses or when added to other products.
Geraniums are non-toxic to humans. They are used in many soaps and shampoos, but they are also edible and used in various dishes. Geraniums are mildly-toxic to dogs and livestock, but these plants are toxic to cats. You should keep all animals away from this plant.
Despite the fact that people can eat hostas, they are toxic to dogs, cats, and horses. Hostas contain saponin, which is toxic when ingested by animals and irritates their skin.
Hyacinths contain oxalic acid, which is found in the flowers, leaves, and stems in small quantities. The highest levels are found in the bulbs. Oxalic acid is highly poisonous to people, dogs, and cats, causing burns and other severe symptoms.
Hydrangeas are poisonous, and they are not edible. They contain cyanogenic glycoside in the buds, flowers, and leaves, and they cause diarrhea, vomiting, and depression. If your children or pets ingest hydrangeas, you need to seek medical attention, even if they are not yet showing symptoms.
There are over 45 different types of Juniper, and the berries all contain a powerful oil called Thujone. This oil can cause an upset stomach, diarrhea, or kidney problems if large quantities are eaten. Some varieties have low amounts of Thujone that are considered safe, including Juniperus communis, which is used to make gin, some food dishes, and medicines.
Mistletoe plants and their white berries are poisonous to humans due to the Viscotoxin and Pharatoxin compounds found in them, which can cause problems when ingested. The berries and plants are also poisonous to animals due to the pharatoxin viscumin and toxalbumin found in the plant.
Morning glory seeds are poisonous, particularly if they are consumed in large quantities. They need to be kept away from children and pets because they can be dangerous. They contain the toxin, lysergic alkaloids, which can cause a lack of coordination and agitation. If the foliage is eaten, it can cause nausea or vomiting.
While the red mulberry is not poisonous for people, all parts of the white mulberry except the ripe fruit contains milky sap that is poisonous to humans. The sap is latex. If people eat fruit that isn’t ripe, they can get an upset stomach or even hallucinations.
Nandina is also known by the common names heavenly or sacred bamboo. All parts of the plant contain cyanide compounds. When ingested, the cyanide decomposes in the body to form hydrogen cyanide which can be fatal. The amount of berries consumed plays a role in the severity of the poisoning.
Peace lilies are poisonous. They contain calcium oxalate crystals, which can cause serious oral irritation if they are eaten. They can also cause an allergic reaction of swelling of the tongue, mouth, and lips. Other symptoms include nausea, vomiting, and diarrhea. It is safe to have these plants in your home as long as nobody ingests them.
Peonies are among the many plants that are toxic to both animals and humans. Even though these plants are toxic, they are still planted in gardens and parks around the world, making them a bigger threat. You should try and keep your children and animals away from this plant.
Poke berries are more poisonous when green than when they are ripe. Poke berries contain saponins such as phytolaccagenin, toxic to humans and most mammals. Symptoms of Poke berry poisoning are nausea, vomiting, diarrhea, and abdominal pain. Symptom severity will depend on the amount consumed.
All species of poppy contain isoquinoline and phenanthrene alkaloids which may be helpful in small doses but are toxic with uncontrolled ingestion. The alkaloids are found in a poppy’s leaves, flower, stem, and seeds. Poppies are poisonous to people, dogs, cats, horses, and livestock.
Rhododendrons are poisonous to people, dogs, cats, horses, livestock, birds, and some insects. Rhododendrons contain grayanotoxin, a richly oxygenated diterpenoid found in all parts of the plant, including the nectar. The poison acts quickly once ingested, and the consequences can be fatal.
Both Kalanchoe and Euphorbia succulents pose a mild threat to humans. You should keep pets away from these succulents as well in conjunction with plants like Aloe, Crassula Ovata (Jade plants), Senecio Rowleyanus (String of Pearls), and Sansevieria Trifasciata (Snake plants).
There are numerous types of sumac trees, including evergreen and deciduous plants. One of these is known as poison sumac and releases an oil known as urushiol, which is highly toxic, causing a severe rash. The urushiol rash can last for several weeks, and there is no known antidote.
Tiger lilies are non-toxic to humans. They are non-toxic to most animals until a certain point. Ingestion of too much of this Lilly can cause gastrointestinal discomforts. Tiger lilies are highly toxic to cats. Consumption of even one or two flower petals can result in severe illness and even death.
Tomatoes are members of the nightshade family, and they produce an alkaloid called tomatine. Tomatine is toxic, but it isn’t deadly. However, if you eat a lot of it, it can cause stomach problems, liver, and possibly heart damage. This alkaloid is present in the leaves, stems, and unripe green tomatoes.
Tulips are poisonous. They contain alkaloid glycosides in all plant parts except the flower petals, with the highest concentration in the tulip bulb. People, dogs, cats, horses, livestock, rabbits, hamsters, and guinea pigs can be poisoned by tulips. The symptoms depend on the amount ingested.
Wisteria is a toxic plant with most of the toxins concentrated in the seeds and seed pods. The toxins wisterin and lectin cause symptoms of poisoning if wisteria is ingested.
Yew berries are red berries that surround a seed. The red flesh of the berry is not poisonous, but the seed is highly toxic. The poison from yew berry seeds can be absorbed through the skin or ingested when the berry is eaten. Yew berries are poisonous to people, dogs, cats, and livestock.
Ornamental yucca plants are not poisonous to humans, and some species have edible seeds, flowers, fruits, or stems. While yucca saponins are not toxic if ingested in small doses by humans, they have a more severe effect on dogs and cats. Yucca plants are significantly toxic to dogs and cats. The plants contain steroidal saponins which are not easily digested.