Dr. Leonard Perry, Horticulture Professor, University of Vermont
(Previously published by the University of Vermont Department of Plant and Soil Science: Winter Holiday News Article)
Although this article directs most of its attention towards the ill effects of these plants on ourselves, fellow house guests, and pets; these toxic plants may find their way to your pasture field once the holiday season has passed. Be aware of your shared fence lines and how you or your neighbors are disposing of your holiday plants this year. And remember, just because other wildlife species can and will consume some of these plants doesn’t mean that they are suitable for your livestock counterparts. Winter is a critical time period as many small ruminant producers are gearing up for lambing and kidding this winter and spring. The last thing that we want to do is lose a pregnancy as a result of disposing some of these plants.
Several of our favorite holiday plants should be kept from children, pets and livestock, yet often they pose no serious danger in small amounts. There are many other and more toxic substances to children in homes to be mindful of, especially cosmetics, cleaning products, and personal care products.
The poinsettia (Euphorbia pulcherrima), the most popular flowering potted plant for indoors, has gotten a bum rap for a number of years. It’s been falsely accused of being poisonous, yet no deaths from this plant have ever been recorded. In fact, research studies at The Ohio State University have proven
that poinsettias present no health hazard.
The rumors arise from a highly questionable report of a single fatality in Hawaii more than 80 years ago, a child who reportedly died after eating one leaf. However, that doesn’t mean the poinsettia doesn’t have mildly toxic properties. If ingested by pets or humans, it can irritate the mouth and stomach, sometimes resulting in diarrhea or vomiting.
The sap may cause a poison ivy-like blistering on contact with the skin on some persons unless washed off immediately. That’s why it’s important to place poinsettias, and other holiday plants, out of the reach of children and curious pets. Keep in mind that pets and people may differ in what plants are toxic, and to what degree. Kalanchoe, for instance, is not listed as toxic for people but is mildly toxic for pets.
How safe are other holiday plants to humans? Here’s the rundown on some common plants which have toxic properties.
HOLLY (Ilex): Branches are used during the holidays in arrangements for the shiny (but prickly) dark green leaves and berries. Eating the bright, red berries of this plant usually result in no toxicity in small quantities. Large quantities cause nausea, abdominal pain, or vomiting.
JERUSALEM CHERRY (Solanum pseudocapsicum): This potted plant has been more popular in decades past, but still can be found during the holidays (so also called Christmas Cherry) for the rounded red fruits against the dark green leaves on a plant about a foot high. Every part of this plant contains the toxic substance solanocapsine, especially in unripened fruits and leaves. Eating the fruit or foliage will adversely affect the heart and can cause a range of symptoms including stomach pain, vomiting, headache, drowsiness, to others more severe.
MISTLETOE (Phoradendron serotinum): This plant parasite of deciduous trees in the Southeastern states is used during the holidays for hanging above doorways, and for its white berries. While most exposures result in little or no toxicity, eating large amounts can cause acute stomach and intestinal disorders. These are caused by the chemical phoratoxin, related to ricin (the highly toxic compound from castor bean plants).
YEW (Taxus): The leaves, seeds (not the red fleshy covering), bark, and twigs of this evergreen can be toxic from the chemical taxine, causing breathing difficulties, uncontrollable trembling, and vomiting. Most reported poisonings are from the seeds, and only result in mild symptoms. Allergic reactions may occur from nibbling on leaves. Yew is another example of the toxicity difference between people and some animals. It is toxic to people, pets, and livestock, but is devoured by deer.
AZALEA (Rhododendron): This holiday plant is mainly grown as a shrub outdoors with thousands of variants. The leaves can be toxic, as is honey made from flower nectar containing grayanotoxins. Perhaps the first written account of rhododendron toxicity was from the 4th century in Greece, depicting the poisoning of ten thousand soldiers from a yellow shrub azalea. One study concluded that eating moderate amounts of azalea posed little danger to humans. Pets and children may be more seriously affected, so it should be kept from them.
CYCLAMEN (Cyclamen persicum): Since the thickened roots (rhizomes) of these are the primary toxic part, containing saponins (similar to those in English ivy), it is unlikely humans (including children) would eat such and be affected, and then only if large quantities are ingested. Skin exposure to the plant sap may cause a skin rash in some people. Pets, especially those that like to dig in pots, should be kept away from cyclamen.
AMARYLLIS (Hippeastrum): The toxic part of this plant is the bulb, which contains lycorine and similar alkaloids. These are the compounds found also in daffodils, and the reason wild animals such as deer know to leave them alone. House pets may not be so wise, so keep these away from them. Ingestion by humans is unlikely, with small amounts producing few or no symptoms.
For more details on toxic plants of all types, including common houseplants, consult the second edition of the Handbook of Poisonous and Injurious Plants by doctors Nelson, Shih, and Balick. From Springer publishing, it is one of the most authoritative, up-to-date, and affordable references for human poisoning by plants, and is used in many poison control centers.
A couple of the more extensive websites to check out plants poisonous to humans are from North Carolina State University (gardening.ces.ncsu.edu/) and the University of California at Davis (ucanr.edu/sites/poisonous_safe_plants). There are several good online resources to check on toxicity of plants to pets, one being the American Society for the Prevention of Cruelty to Animals (www.aspca.org/pet-care), which also lists plants toxic to horses. Several sites, including Cornell University (poisonousplants.ansci.cornell.edu), deal specifically with plants poisonous to livestock.
If you suspect poisoning, seek immediate professional help. Unless told to do so by a doctor, do NOT make the person throw up. Call your local poison control center, often at your local hospital. Or, you can call the national poison control center hotline, toll-free, (800-222-1222) and talk with poison control experts. This service is available anytime, and can answer any questions on poisoning, even if not from plants and even if not an emergency.