Abstract: The main original plant of the traditional Chinese drug Mianbeixian has been considered as Dioscorea septemloba Thunb. for a long time. Based on morphological, light microscopical, scanning electron microscopical, chromatographical and ultra-violet spectroscopical examinations and in comparison with the Japanese material, the Chinese one is proposed as a newspecies-Dioscorea spongiosa.

Key words: Dioscorea spongiosa, D.septemloba.