Ginger is a tropical plant that has green-purple flowers and an aromatic underground stem (called a rhizome). It is commonly used for cooking and medicinal purposes. Historically, ginger has been used in Asian medicine to treat stomach aches, nausea, and diarrhea. Today, ginger is used as a folk or traditional remedy for postsurgery nausea; nausea caused by motion, chemotherapy, and pregnancy; rheumatoid arthritis; osteoarthritis; and joint and muscle pain.