Injury to the oral mucous membranes caused by the common houseplant, dieffenbachia. A review.

The common houseplant, dieffenbachia, causes painful edematous swelling of the oral mucous membranes when chewed. This property, which is well known to the staffs of poison control centers, can be dangerous to the unwary or to victims of practical jokes. The microscopic features of the injury are those of acute inflammation, but the nature of the plant's toxicity remains controversial. The numerous needles (raphides) of calcium oxalate, which are contained in specialized cells (idioblasts) in the plant, and proteases have both been implicated. When stimulated, the idioblasts fire the raphides with some force for a distance of two to three cell lengths. One possibility is that the local toxicity of dieffenbachia may be caused by a combination of this mechanical release of the raphides, which results in traumatic injury, and the effects of a chemical toxin carried on their surfaces and in their grooves.