Abstract: The Chinese traditional drug, Xu-duan (Hsu-duan) has been reported through years being the root of either Dipsacus asper Wall. or D. japonicus Miq. Problems aroused by recent investigations are: (1)Is it really the Indian species D.asper extending into SW China and furnishing the Xu-duan root? (2) Does the above mentioned the only source of Xu-duan or the other species, D. japonicus, also yields the Xuduan root?To answer these questions, the junior author, T. M. Ai made field explorations in the main production area to collect the plants with the medicinal parts. He also inspected the crude drugs of the market and consulted the institutes for drug control in Hubei and Sichuan. Conclusions came out as follows: (1) The best quality Xu-duan is produced in W. Hubei, and the sole source is an undescribed plant which has been misidentified as D. asper Wall. in the past half century, and now described here as Dipsacus asperoides Cheng et Ai, sp. nov. This new plant differs from D. asper in having bracteoles with longer mucron, involucel furrowed and corolla tube with a slender tubular base (f. 1,A: a,a'). (2) A species from SE Sichuan which is almost identical with D. asperoides in vegetative appearance, but possesses dark purple flowers with different floral structure, is described here as D. atropurpureus Cheng et Yin, **sp. nov. Its roots are sometimes used as Xu-duan in small scale. There is another species with purple flowers distributed in the same area as D. atropurpureus, D. fulingensis Cheng et Ai, sp. nov. Its roots, however, are fibrous and hard, and not fit for medicinal use. (3)Dipsacus japonicus Miq. with its spiny habit and pinkish flowers, though widely distributed in China,has never been used as Xu-duan due to the fact that its roots are dry and exceedingly hard in texture.