Poisonous Plants

By Jiordana Stark, Master Gardener

Q: I know that Poinsettias are a poisonous plant, but can you tell me what other house or garden plants are too? My grandchildren are coming to visit and they are constantly putting everything in their mouths. It worries me no end. Betty F. Los Osos

There are over 500 species of poisonous plants that grow in the United States. Many of the most beautiful trees, shrubs, vegetables, and vines are poisonous, but that does not mean that they should be eliminated from your garden. It does mean that, if you spend some time identifying the plants in your house and garden, and develop a plant identification file, plant poisoning can be prevented.

By knowing your garden, and calling your plants by name (no, you don’t have to learn the botanical names, common names are just fine), the garden may become “learning friendly”. You can then pass what you have learned on to your grandchildren. First, know if the plant is poisonous and, if so, which parts. For example, many of our common lilies are poisonous, including the toxic berries of the common Lantana, the long spikes of the Foxglove, the colorful carnation and chrysanthemum, mistletoe, daffodils, sweet peas, tulips, iris, oleander and, of course, poinsettia. With some, the whole plant is poisonous; with others, it might be the flower, fruit, leaves, stem or sap.

Even some of our common fruits and vegetables contain toxic plant parts. For example, eating raw, green, young shoots of asparagus can cause dermatitis. The red berries on the feathery asparagus branches are poisonous. Our garden tomato is closely related to the deadly nightshade and, although we all know that fresh tomatoes are harmless, the leaves and vines contain alkaloid poisons. Children have been poisoned from making a “tea” from tomato leaves.

All parts of the peach tree, with the exception of the edible peach fruit, contain cyanide-producing compounds that are released when peach seeds, bark, and leaves are eaten. Children have died from eating the seeds, chewing on peach twigs, and making “tea” from peach leaves.

Teach your children not to eat seeds, berries, leaves, or mushrooms, and not to make “tea” out of their favorite plants. Do not assume a plant is non-toxic because birds or wildlife can consume it without harmful effects. Do not use twigs as sticks for roasting hot dogs. The twigs may contain toxins which cooking will not destroy.

With today’s food trends of edible flowers in our salads and fresh herbs in our sauces, it is more important than ever to know your garden. Keep it a safe and enjoyable haven for you, your grandchildren and your pets. There are several excellent websites with additional information:

Know Your Plants---Safe or Poisonous? at http://envhort.ucdavis.edu/ce/king/PoisPlant/

California Poison Control System at http://www.calpoison.org/home.html

Poisonous Plants—Dogs & Cats at http://www.cah.com/library/poisplts.html

University of California Cooperative Extension Master Gardener Volunteers can provide additional gardening information upon request. Call the San Luis Obispo office at 781-5939 on Mondays and Thursdays from 1 to 5 PM.  You may also call the Paso Robles office at 237-3100 on Wednesdays from 9 AM to Noon.  The San Luis Obispo Master Gardener website is at http://groups.ucanr.org/slomg/. Questions can be e-mailed to mgsanluisobispo@ucdavis.edu.

Some of the websites mentioned are sites outside of the
University of California domain. No endorsement is intended of products, services or information, nor is criticism implied of similar sites that are not mentioned.