   Poisonous Landscape Plants - July 7, 2004 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Many common landscape plants are considered poisonous or toxic. Everyone knows that oleanders are toxic, but what about English ivy, boxwood, lantana, and philodendron? A poisonous plant can affect people and animals in a range of ways. Exposure to toxic plants may produce symptoms ranging from dermatitis, local mucous membrane irritation, stomach upset, convulsions, heart beat irregularity, serious illness, and death in rare cases. The average person does not go about eating any plant that they come across. However, children, pets, and others sometimes do. Remember that individuals have varying tolerances to these poisonous compounds. There are also a number of variables that determine how severe the poisoning symptoms may be, such as the age, weight and health status of a person in relationship to the quantity of the plant ingested as well as the form that the plant was in at the time of ingestion (i.e., cooked versus raw, ripe fruit versus unripe fruit, etc.). Many plants have developed poisonous properties over generations to discourage herbivory by animals and insects. Think of these toxins as a sort of innate pesticide that protects them from potential enemies. A plant’s poisonous properties should not discourage you from growing them. Just be aware of those that can pose a potential risk. There is not enough room here to include a comprehensive list of poisonous landscape plants, but below I will discuss a few that are used in our area: Oleander (Nerium oleander) - all parts are poisonous and contain several toxins that affect the heart. Animal poisonings usually occur when trimmings are thrown into a corral. Human poisonings have occurred when oleander twigs were used for meat skewers. Yew (Taxus sp.) – leaves, seeds, and twigs are poisonous and contains many compounds: some of which are toxic. Many native deer can tolerate ingestion. Livestock death can occur without symptoms. Lantana (Lantana sp.) – green berries of some species are poisonous and contain an atropine-like compound called lantodene. Sheep, cattle, horses, and humans have been poisoned by Lantana. Black Locust (Robinia pseudoacacia) – bark, leaves, and seeds are poisonous. Children may get poisoned by eating the bean-like seeds. Virginia Creeper (Parthenocissus quinquefolia) – the ripe berries are suspected to be poisonous although poisoning and death in humans has been suggested in the literature. The Internet is loaded with information about poisonous plants. As always, use caution when getting information from the internet. I recommend only getting information from university or government web sites. Some resources I used when researching poisonous landscape plants follow: Cornell University Poisonous Plants Database at www.ansci.cornell.edu/plants/alphalist.html; University of Georgia Cooperative Extension Factsheet Poisonous Plants in the Landscape at www.ces.uga.edu/Agriculture/horticulture/H-00-056.htm; and Montana State University Cooperative Extension Factsheet Poisonous Plants in the Home Landscape at www.montana.edu/wwwpb/pubs/mt9902.pdf. Prevention is the best way to prevent toxic plant poisoning. You really should identify all the plants in your landscape. If you need help, you can bring a sample to your local nursery or Cooperative Extension office (a flower or fruit is often helpful). If you have a poisonous plant emergency call the Arizona Poison and Drug Information Center at 1-800-222-1222. If a person is having difficulty breathing, experiencing seizures, or is unconscious, then call 911 immediately. Thanks to Sedona resident Karen Willey for suggesting this topic. The University of Arizona Cooperative Extension has publications and information on gardening and pest management. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at mgardener@verdeonline.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/. |