I get a lot of questions about poisonous plants. Many species, both interior, and exterior can contain poisonous chemicals. Most aren’t a major concern. In fact, many of our common houseplants are considered poisonous, but they are found everywhere. Often, we see them in public places frequented by pets or small children.
Poinsettias are common Christmas decorations, and they have poisonous latex in them. If we get this latex on our hands and then rub our eyes, we’ll be sorry. However, the same can be said for touching habanero peppers.
Elderberries are quite poisonous prior to ripening. In large quantities, nutmeg can cause dizziness, drowsiness and seizures. Apple seeds and cherry pits contain cyanide compounds. Potatoes exposed to light contain glycoalkaloids. These can even cause death. Raw cashews contain the same compound found in poison ivy.
Pencil cactus (Euphorbia tirucalli) is a poinsettia relative. It has a reputation for being extremely poisonous. I’ve even had folks ask me why we have it in our greenhouses. The answer is simple. We keep poisonous cleansers under our sinks. Who worries about that? We even eat foods containing poisonous components like the ones already mentioned.
I wouldn’t place pencil cacti around unsupervised toddlers or puppies, but they are an attractive and intriguing houseplant for well-lit places. The white latex is the only toxic part, and these plants have no thorns.
They’re great in succulent dish gardens, but after a year or two, they often must be separated and planted by themselves. Eventually, they can become large. I’ve seen these Euphorbias well over six feet tall indoors.
Pencil cacti require very little maintenance and they can be pruned without causing harm to the plant. The white sap can be a skin irritant to some. It will cause severe eye problems for most people.
People allergic to latex are especially susceptible to eye irritations, and in some cases have even gone temporarily blind. Corneas can be totally burned out. I wouldn’t recommend people with latex allergies keeping this plant or others containing latex. Otherwise, washing with soap and warm water immediately after handling will remove the toxins and avoid any problems.
Pencil cacti are also toxic to pets. The sap can cause irritation to the mouth and digestive system, but generally, toxicity is overrated. Many other plants like daffodils are potentially a greater concern for pets. Oleander, Aloe vera, castor beans and tomato foliage are common plants that can be problematic for canines.
Ingesting the sap from pencil cactus is not common. Numerous articles warn us that it’s toxic, but the sap is so bitter I doubt even the most curious toddler could tolerate swallowing enough to be life-threatening.
Dumbcane is another houseplant often touted as extremely toxic. It contains calcium oxalate crystals, which cause burning and tongue paralysis. Symptoms are mild and temporary, and I suspect children and pets wouldn’t consume enough to hurt them.
We have houseplants for decoration, and pencil cacti make striking contrasts to our other plants. Furthermore, any plants with latex are likely to cause skin and eye irritations. Keep that in mind.
Ted Manzer teaches agriculture at Northeastern High School.