An East Indian plant that is a member of the ginger family and is used as a spice and food color. The underground stems are used in some cultures to treat certain stomach problems. The substance in jiang huang that gives it a yellow color (curcumin) is being studied in the treatment of cancer, Alzheimer disease, cystic fibrosis, and psoriasis. The scientific name is Curcuma longa. Also called Indian saffron and turmeric.