Ginger, the underground stem, or rhizome, of the plant Zingiber officinale has been used as a medicine in Asian, Indian, and Arabic herbal traditions since ancient times. In China, for example, ginger has been used to aid digestion and treat stomach upset, diarrhea, and nausea for more than 2,000 years. Ginger has also been used to help treat arthritis, colic, diarrhea, and heart conditions. In addition to these medicinal uses, ginger continues to be valued around the world as an important cooking spice and is believed to help treat the common cold, flu-like symptoms, headaches, and even painful menstrual periods. Native to Asia where its use as a culinary spice spans at least 4,400 years, ginger grows in fertile, moist, tropical soil. Ginger is a knotted, thick, beige underground stem (rhizome). The stem extends roughly 12 inches above ground with long, narrow, ribbed, green leaves, and white or yellowish-green flowers.