Q: Recently my wife and I were at a restaurant. I saw there a plant that I was told was a pencil tree plant. I asked for a cutting. The wound produced a white sticky sap which got on my fingers and which I accidentally rubbed in my eyes. At once there was trouble: severe burning and watering, blurred vision, dizziness and confusion. At the emergency room I was told that I had latex poisoning and that if immediate medical attention had not been given, corneal damage and possible blindness could have resulted.

A: Your pencil tree, Euphorbia tirucalli, is well known to produce a particularly caustic sap. Any plant in the Euphorbia genus should be considered poisonous. Even though poinsettia, Euphorbia pulcherrima, has been shown not to be dangerous, the sap should be avoided.

Another plant juice to avoid is that of elephant ear. It is a member of the arum family, as are spathiphyllum, dieffenbachia and caladium. All have sap that contains calcium oxalate crystals, which causes “oral irritation; intense burning and irritation of the mouth, lips, tongue; excessive drooling; vomiting; and difficulty in swallowing” when ingested.

Plants have many ways to protect themselves beyond thorns and prickles. Your experience is a caution to us all.