A large, starchy root. Fresh chunks are simmered for hours with pork bones and red beans in Cantonese soups; dried pieces are sold as a Chinese herbal medicine, and the starch is sold as kudzu powder.
葛根 has been a staple of traditional Chinese medicine for over 2,000 years - it is the headliner ingredient in 葛根汤, a classical formula recorded in Zhang Zhongjing's 《伤寒论》 (c. 200 CE) for stiff necks and early-stage colds. You'll find 葛根 powder, tea, and noodles all over Chinese health-food shops.