Abstract:Objective:To Study the characteristics of Herba Spirodelae(Spirodela polyrrhiza)and its adulterants S.oligorrhiza and Lemna minor for identification.Method:The characteristics were compared and identified morphologically and histologically.Result:The morphological and histological characteristics of S.polyrrhiza,S.oligorrhiza and L.minor are different from each other.Several tables,keys and drawings are given.Conclusion:The main macroscopical and microscopical characteristics can be used fo differentiate S.polyrrhiza from its adultrants.