Poison Plants, Indoors and Out
The vast majority of the plants in our lives are not poisonous, and with a little knowledge and common sense, we can avoid those plants that might cause problems.
To be classified as poisonous, a plant simply needs to produce some type of adverse reaction when people are exposed to it. Many external allergic reactions account for some plants to be called poisonous. Some plants can also cause internal poisoning when ingested. The part of a plant that actually causes the reaction or poisoning is called a toxin. Unfortunately, that same plant may appear on lists that are classified both as safe and as poisonous.
One of the most dangerous aspects of dealing with poisonous plants is variability. Some people may react severely to poison ivy, while others could pitch a tent in the middle of a patch and not be bothered in the least. The same variability applies to many plants. To further complicate things, factors such as the time of year, the type of growing season and the level of maturity may affect the level of toxicity in a plant. The age, size and health of the person exposed may also influence toxicity.
The bottom line when dealing with a poisonous plant is to contact a poison control center if you have any doubts about a plant you, your children or pets are exposed to. In the meantime, before you have a potential problem, make it a point to find out about the plants sharing your life.
Guidelines to Prevent Poisoning
Do not eat any part of a plant that you cannot identify or if you are uncertain that it is safe.
Keep house plants out of the reach of children and pets.
Avoid landscape plants that are poisonous if you have children or pets.
Make a special effort to teach children about plants.
Store seeds and bulbs away from food preparation areas.
Most poisonous plants can be easily confused with similar nontoxic plants. Learn to identify them correctly. One of the most highly toxic plants in our area is poison (water) hemlock. It looks like a large wild carrot or Queen Anne's lace.
Keep a list of the plants in your landscape. Whenever possible, find out the botanical name as well as the common name.
Setting the Record Straight: Dealing with Common Misconceptions
Just because an animal eats a plant, it doesn't mean it's safe for humans. For instance, furry creatures are rarely bothered by poison ivy. The opposite is also true. Plants that are safe for humans may be toxic to animals. For more information call the animal poison control center at 612-337-PETS.
Even if a plant has traditionally been used in teas and medicines, it may not be safe. We are now learning about the possible side effects of plants we thought to be safe or even curative, for centuries. For instance, comfrey is now being investigated as a possible carcinogen.
It used to be said that cooking will destroy toxins, but this is not always true. For example, young pokeweed greens have been traditionally eaten by boiling them, pouring off the tainted water, adding fresh water and repeating the process several times. Yet mature foliage, roots or berries of the plant can be very toxic whether cooked or not. Elderberries can be used in jams when cooked, but may make you ill if eaten fresh.
Any mushrooms that grow in your yard should be considered poisonous. There are many risks involved in trying to distinguish the different types of mushrooms.
Just because it is safe for humans, does not mean it is safe for animals. Even though some people have dogs who love chocolate, too much can be toxic.
You cannot always safely dispose of poisonous plants by burning or composting. The toxins might become part of the smoke and be inhaled.
Just because one part of a plant is safe, it doesn't mean the whole plant is safe. Tomatoes are a perfect example. The fruit is the only edible part of the plant. Rhubarb stems are edible and rhubarb leaves are toxic. Apricot fruits are edible, but their seeds are poisonous.
Being able to handle something toxic without a reaction doesn't mean it can be safely ingested. Aloe may be great for soothing burned skin, but when eaten, it can be a powerfully painful laxative.
The amount of exposure can determine if a plant is poisonous. Licorice is a great flavoring for foods and candies but used in excess, it can cause problems for the heart and kidneys.
Poisonous Plants Commonly Found in Our Area
We receive the most questions about nightshade, poison ivy, poinsettia and dieffenbachia. The most dangerous plants that grow naturally in our area are nightshade, poison ivy, poison (water) hemlock, datura (jimsonweed) and mushrooms. But even though a plant doesn't appear on our list doesn't mean it isn't dangerous. A more extensive list appears later in this information sheet. Call the poison control center with any questions or for additional information.
It is probably the most common and dangerous plant because it grows wild and has colorful berries that are attractive to children. This plant is an annual, also known as deadly or black nightshade (Solanum americanum or S. nigrum). The plants usually appear as volunteers (seeded by birds). While the plants can grow in lawns, mowing tends to keep them from flowering or fruiting. The foliage and flowers closely resemble their cousin, the potato. Plant habit varies from sprawling to upright and heights may reach 2 feet. Flowers are white and borne in clusters all over the plant. The fruits start out green and go through several stages, ending up dark purple or black. The fruits are small, about the size of a large BB. Initial symptoms caused by eating the berries, especially green berries, are paralysis of the tongue and dilated pupils. Call the poison control center immediately if consumed. Nightshade can be pulled, sprayed or cut down.
This plant has earned its place on our list, even though it may not be as fatally toxic as others. Some people are immune to poison ivy and some may get a slight, itchy rash. There are those that are sensitive, resulting blistering, itching, swelling and discomfort. It can be so extreme that it requires hospitalization. Poison ivy (Toxicodendron radicans) is a woody perennial in our area. It typically grows as a ground cover, less than a foot tall, and creeps along the ground. The leaves are divided into three leaflets, oval and pointed. The middle leaflet is longer than the two on the sides. All parts of the plant contain toxins. This includes the leaves, stems, woody vines and roots. Skin irritation usually appears within 24 hours. Another method of infection is exposure to smoke from burning poison ivy plants or pets that have been in contact with it. Over-the-counter treatments are available for mild cases. If severe, contact a doctor. Poison ivy can be difficult to eradicate but it will respond to repeated treatments with herbicides.
Widely thought to be poisonous, this plant is, at most, a skin irritant. It is part of the Euphorbia family. It produces a milky, sticky sap that can result in a rash. Tests have shown that an average child would have to eat a bowlful of colored bracts (leaves) before showing any effect. Since they don't taste good, that is very unlikely. If a skin irritation occurs, or if you are concerned, call a physician or the poison control center immediately.
A very popular indoor plant, dieffenbachias (also known as dumbcane) can cause some problems if eaten. This is a common indoor tropical with large leaves, usually mottled or variegated yellow and green. Touching the leaves will not cause any problems. When eaten, the toxin causes stinging and burning of the mouth and throat, and may also cause vomiting and swelling. Call a physician or the poison control center immediately for further information if you suspect internal exposure.
Technically, these are two different plants, Cicuta maculata (poison hemlock) and Conium maculatum (water hemlock). These plants are often confused and their common names are used interchangeably. They are huge, often growing more than 5 feet tall, with finely-cut compound foliage and large white flowers. They look a lot like wild carrot, Angelica or Queen Anne's lace. It is in the parsley family and all parts of it are extremely poisonous. In one (Cicuta), the most toxic is the root system, resembling sweet potatoes, parsnips or other similar roots. In the other (Conium), the foliage and stems contain the most toxins. On both, the stems are hollow and children are often tempted to put them in their mouths. Symptoms can be very severe and usually occur within an hour or two of ingestion. They include stomach pains, nausea, difficulty breathing. Hemlock can be fatal. Both forms are easily destroyed by herbicides or they can be dug out.
Datura (Jimsonweed, Moonflower or Thorn Apple)
This is another annual plant that volunteers in gardens and along the edges of fields and roads. Datura stramonium is in the same family as nightshades and potatoes. It grows in a bush form and can grow to 4 or 5 feet tall. The leaves give off an unpleasant odor when bruised. The flowers are large and look like big morning glories. The wild variety blooms white and the type called moon flowers are old-fashioned bedding plants. Datura are white or pale lavender and include one version with royal purple blooms. All varieties are poisonous. After blooming, a prickly fruit forms that is almost the size of a golf ball and contains the seeds. All parts of the plant including fruits and seeds are poisonous. Symptoms are headache, nausea, thirst, dilated pupils and hallucination. Datura poison can be fatal. Control the plants with herbicides or cut and destroy them.
Even though there are thousands of kinds of mushroom and only a few of them are poisonous, it is best to leave mushroom gathering to the experts. Mushrooms are decay mechanisms and are often infested with the larvae of fungus flies and bacteria. They can also absorb chemicals used on the lawn. Mushrooms that commonly appear in the yard during a cool rainy part of the season are also called puffballs or toadstools. Some of them are poisonous and only an expert can safely identify which. There are no chemical methods of destroying/discouraging mushrooms. Simply watch for them, and destroy them as they appear by raking and bagging them.
Common Plants with Poisonous Properties
(Some are only mildly toxic, others are dangerous)
Garden Annuals - Perennials
Bleeding Heart Dicentra
Castor Beans Ricinus
Sweet Pea Lathyrus
Morning Glory Ipomea
Poison Ivy Toxicodendron
Creeping Charlie Glechoma
Hemlock Cicuta and Conium
Jersusalem Cherry Solanum
Bird of Paradise Strelitzia
Crown of Thorns Euphorbia
Rosary Vine Ceropegia
Bulbs, Tubers, etc.
Fall Crocus Colchicum
Elephant Ears Colocasia
Lily of the Valley Convallaria
For more information or in case of emergency, contact your local poison control center or physician.
Emergency Phone Number–All of Minnesota