Life SciencesBotanyPlant SciencesPlant AnatomyPlant CytologyPlant HistologyCell Wall StructureEpidermal AnatomyNeedle AnatomyOxalate Crystal ToxicityParenchyma CellsToxicity Of Oxalate-containing Plants
To the Editor:— A case of toxicity resulting from biting into the stem of dumb cane ( Dieffenbachia sequine ) was reported by Drach and Malone ( JAMA 184 :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 species 1,2 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.