The commercial standards of Dendrobium medicinal materials in Yunnan are very complicated. 1. The principal commodities of these materials include: 1. Xi-fengdou (spiral Dendrobium): They are divided into three classes, i.e. 1, 2 and 3, but recently Diaolan-fengdou (rough spiral Dendrobium) was discovered. 2. Huangcao (yellow herb Dendrobium): They are classified as Xi-huangcao (slender Dendrobium), Cu-huangcao (thick Dendrobium), Bian-huangcao (oblet Dendrobium), Xiaogua-auangcao (littlemelon Dendrobium) and Xian-huangcao (freshly Dendrobium). 2. nonprincipal Huangcao commodities in Yunnan include: Cha-huangcao (branch Dendrobium), Xianggun-huangcao (stick Dendrobium) and Yougua-huangcao (melon Dendrobium).