The poisonous plant dumb cane ("Dieffenbachia") contains the substance and on ingestion can prevent speech and be suffocating. It is also found in sorrel, rhubarb (in large quantities in the leaves), cinnamon, turmeric and in species of "Oxalis", Araceae, "Arum italicum", taro, kiwifruit, tea leaves, agaves, Virginia creeper ("Parthenocissus quinquefolia"), and "Alocasia" and in spinach in varying amounts. Plants of the genus "Philodendron" contain enough calcium oxalate that consumption of parts of the plant can result in uncomfortable symptoms. Insoluble calcium oxalate crystals are found in plant stems, roots, and leaves and produced in idioblasts.