What is the most toxic indoor plant?
Dumb-cane (Dieffenbachia), in the Araceae family, has plant parts which contain oxalate crystals. If ingested these can cause the tongue to swell so severely that breathing stops. Crown of thorns (Euphorbia), a succulent in the Euphorbiaceae family, has toxic sap which can be quite irritating to the skin. All parts of the plant contain needle-like calcium oxalate crystals, which if chewed or eaten, can cause immediate pain or a burning sensation and swelling of the lips, mouth, tongue and throat. The sap may cause contact dermatitis and eye irritation.