What houseplant's leaves contain calcium oxalate crystals that cause mouth burning? Dumb cane is the answer, the common name for plants in the genus Dieffenbachia. It is a popular tropical houseplant because its large, patterned leaves tolerate relatively low light.
The leaves contain needle-shaped calcium oxalate crystals called raphides. When a leaf is chewed, the crystals irritate the mouth and can cause intense burning, numbness, drooling, swelling, and difficulty speaking or swallowing. The name “dumb cane” refers to the temporary speechlessness that can follow exposure, not to the plant being permanently paralysing.
Dieffenbachia is sometimes described as deadly, but that is usually an exaggeration. Most exposures produce painful yet temporary symptoms. Severe swelling is possible, particularly after prolonged contact with the mouth or throat, and can interfere with breathing. Children and pets are at greatest risk because they may chew the leaves.
Dumb cane is often confused with philodendron and pothos, which are also aroid houseplants containing irritating calcium oxalate crystals. Its distinctive broad leaves, commonly marked with cream or pale-green patterns, help distinguish it from those trailing or differently shaped plants.