Abstract: This paper reports the result of comparative anatomical studies on medicinal roots of 53 species and varieties in the genus Aconitum from China. The anatomical structures of the roots can be classified into 6 types and 18 subtypes according to the level of their evolution. The anatomy of Aconitum roots is discussed in relation to phylogeny based on chemotaxonomy, cytology and other related disciplines. It was found that the six types of Aconitum roots are correlated with chemical components, chromosomes, toxicity and the gross morphology. The relatively advanced Types I and II roots always contain highly toxic alkaloids of diterpenoid diester of aconitine type, distributed mainly in Ser. 3, 5-11 of Sect. Aconitum of Subgen. Aconitum, while the relatively primitive Types III, IV and II roots with small diameters contain mainly atisine and aminal alcohol alkaloids, which have lower toxicity, present in Subgen. Gymnaconitum and Ser. 1, 2 of Sect. Aconitum of Subgen. Aconitum. The primitive Types V and VI roots of Subgen. Lycoctonum contain mainly the most low-toxic alkaloids of lycoctonine Type. The result is of significance both in theory or practice for the development of medicinal plant resourcesand the safety of clinical usage of these of plants.

Key words: Aconitum, Subgen. Lycoctonum, Subgen. Aconitum, Subgen. Gymnaconitum, comparative anatomy, phylogeny