Guest Author - Wendy Lee

The most popular question that I receive both while working and via comments from readers is “Is this plant poisonous?” As with most all things, too much of something can make you, family, or pets ill. Poisonous plants are broken into four main categories based upon the reaction caused by said plant. 1. Oxalates; 2. Toxic or potentially toxic; 3. Dermatitis; 4. Unknown. The following are descriptions of each type of toxicity, example plants and advice as how to assuage the symptoms; advice which is NOT, under any circumstances, to be used as a sole means of medical attention. Seek medical help as soon as possible if any condition worsens or persists.

Oxalates are an organic compound that many plants have as a defense against being eaten in their natural habitat. The most common reaction to oxalate crystals is swollen contact areas that may also be itchy or otherwise irritated. Oxalates are mostly found in the Araceae family (Peace Lilies, Calla Lilies, Philodendrons [Heart Leaf, Cut-Leaf, Monstera, etc.], Nephytis [Arrowhead], Arum, Chinese Evergreen, and Dieffenbachia [Dumb Cane]). These crystals located all throughout the plants leaves, roots, and stems. Most common of these afore mentioned plants to cause these symptoms are Philodendron and Dieffenbachia; usually affecting young children.


A toxic or potentially toxic rating is unfortunately vague as the plant can cause anything from a mild irritation to organ damage and possible organ failure depending upon the plant. Best advice is to wash the affected area and contact poison control. Plants associated with this rating are English Ivy, Narcissus (daffodils and paper whites for example), Euphorbia (various cacti), Bird of Paradise, and String of Pearls.


Dermatitis is a condition that many people are aware of, one form of which that many are familiar with is the rash caused by poison ivy. While all forms of botanical dermatitis won’t necessarily take that form, it is best to wash the area with warm soapy water and avoid contact with the eyes. If said rash persists or worsens medical help may be required. Plants that may cause this issue in humans and animals are not limited to but include: Schefflera (Octopus Plant, Marigolds, and Ficus (Fiddle leaf and Benjamina).


Finally, the fourth category of toxicity is Unknown. This basically means that not enough research has been done to found out why or how a certain plant is poisonous, either to humans or animals. Again, basic first aid of washing the affect area with warm soapy water is the best known way to abate the symptoms. Examples of plants in this category include Sweet Pea, Spider Mums, Poinsettias, and), Sansevieria (Snake plant or Mother-in-Laws Tongue).


If you are unsure as to what plant you came in contact with to cause irritation be sure to get a sample large enough to have it identified should medical intervention be required. Also note that even though many common house plants are listed on toxic/poisonous plant lists, for your pets or children to become critically ill it would require them to either be highly allergic to said plant or for them to ingest many of the plants at once.


Again I have to stress that though I may be an expert in the botanical department I am not a licensed medical expert, do NOT take this article as law, if you or anyone else fels that medical attention is necessary take action promptly.