University of Vermont
Department of Plant and Soil Science
Winter
Holiday News Article

HOLIDAY PLANT TOXICITY
Dr. Leonard Perry, Horticulture Professor
University of Vermont
Several of our favorite holiday plants should be kept from children and
pets, 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 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.
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