12 Garden and Yard Plants Harmful to Humans

Plants and flowers beautify our lives and property, but the potential for harm is always present even among the most common household varieties. Adults are responsible for teaching children to respect plants and wildlife, including the foliage that grows in one’s own back yard. Listed here are twelve common plants that threaten human health. A few only cause an irritating rash, while others are deadly, even when consumed in very small amounts.

Twelve Common Plants Harmful to Humans

There are hundreds of plant species that are poisonous to humans as well as pets. A few examples commonly found on properties across the United States are given here.

1. Poison Ivy, Poison Oak and Poison Sumac. Woody vines or shrubs native to the United States, these three plants can each cause a nasty rash from the potent component urushiol oil. Burning the plants for disposal only releases toxins into the air, causing problems for anyone that comes in contact with the smoke.
2. Castor Bean. Susan Bristol, in the article, “Wicked Plants” (2009), submitted to AOL (America On Line), cites Dr. Susan Pell, a Molecular Plant Systematist at the Brooklyn Botanic Garden, stating, “… the castor bean plant is actually quite useful as it is processed to help in the production of castor oil. However, the seed coats of these greens are ripe with a toxin called ricin, which according to Pell, prevents a vital protein from helping with cell development.” Just two castor bean seeds may be enough to cause death in an adult.
3. Oleander Plant. Extremely poisonous. Ingesting the oleander can affect the heart and cause death.
4. Jimson Weed. The plant is a hallucinogen that can cause serious illness or death. It may also be referred to as stinkweed, locoweed, or thorn apple.
5. Euphorbia. The plant looks like a cactus, but the sap can cause inflammation, a rash, and blindness if rubbed in the eyes.
6. Lantana. Lantanas produce beautiful flower clusters, but can also cause skin irritation. Ingesting the plant can cause death.
7. Geraniums. Delightful colorful flowers make geraniums a natural choice for summer gardeners, but handling the plants may cause skin irritation.
8. Daffodil bulbs. Eating the bulbs causes nausea and vomiting, and can result in death.
9. Dieffenbachia. The plant causes extreme irritation and burning to the mouth. It can also cause the tongue to swell, blocking the airway.
10. Rosary Pea. Extremely poisonous. According to the online Web site, Poisonous Plants, in a chart reprinted from materials provided by the Texas State Department of Health and the National Safety Council, “Consuming a single pea from this vine can cause death.”
11. Mistletoe Berries. Eating these causes death in children and adults.
12. Poison Hemlock. This looks like a carrot, but eating it causes death.

Gardening and Landscaping Affects Children, Teens, and Pets

Pets sometimes chew on indoor and outdoor plants, and children are often attracted by pretty flowers and berries. This alone is enough to deter most family gardeners and landscapers from placing toxic plants in or around the home. New home buyers should make it a point to scour front and back yards for dangerous and/or unfamiliar plants.

Teens who know how to grow plants such as cannabis (Marijuana) for narcotic use are just as likely to know about the effects of Jimson weed. In a publication by the Do It Now Foundation, referring to the article, “Jimson Weed: Fast Facts” (2007), the staff states, “All parts of the plant are toxic, so pleasant effects are limited – a big reason the plant is used only by novices.” And, “Psychological effects include confusion, euphoria, and delirium.”

Plants can be as dangerous as they are beautiful. In some cases a single touch of a leaf produces an irritating rash, while plants such as poison ivy and related species are harmful even when burned. Deadly berries and leaves in common decorative plants make the species a threat to pets and children. Plants used as drugs may be attractive to some teens and adults. Recognizing dangerous plants and removing them may prevent an unnecessary tragedy, especially where children and pets are concerned. Wise parents and homeowners know it is important to be able to identify all plants growing on the property. Those plants that are unfamiliar should be properly identified for peace of mind.