To the Editor:—
A case of toxicity resulting from biting into the stem of "dumb cane" (Dieffenbachia sequine) was reported by Drach and Malone (JAMA184:1047 [June 29] 1963).Two types of intercellular crystals are present in the tissue of this popular foliage-plant: "druses," star-like clusters of polyhedral crystals, and "raphides," needle-shaped crystals arranged parallel in compact bundles (Figure). Both are said to be composed of calcium oxalate. Such crystalline inclusions are prevalent in plant tissues, usually in the softer parts (leaves, stems, and fruits), and in a great variety of species1,2 including some eaten with impunity.Dieffenbachia is peculiar in that the raphides are borne not in thin-walled parenchyma cells but inside special cylindrical thick-walled cells which have a nozzle-like aperture at either end.3 On sectioning fresh tissue, the needles may be seen—if one acts quickly—being extruded singly and in rapid succession from the cell orifices.
Dore WG. Crystalline Raphides in the Toxic Houseplant Dieffenbachia. JAMA. 1963;185(13):1045. doi:10.1001/jama.1963.03060130063023