Abstract:Based on morphological data, a phylogenetic analysis was performed to study the circumscription and infrageneric classification of the genus Lysimachia. Parsimony analysis showed that Lysimachia was paraphyletic, with L. crispidens as the sister group to all the other samplings, including those small genera of the tribe Lysimachieae. The monophylies of subgen. Idiophyton, subgen. Lysimachiopsis and subgen. Palladia were supported, while subgen. Lysimachia was found to be paraphyletic. The subgen. Naumburoia，whose status being controversial，was nested within the main simachia group． Subgen．Seleucia，however，was deviated and grouped with Trientatis．It iS noted that in this study most morphological characters are homoplasious and hence only some internal clades rece ive moderate bootstrap support．Further studies，especially DNA sequencing approaches， are needed before an unambiguous phylogeny is achieved for the genus．