Abstract: In this paper, based on the investigation of the distribution and the experiment of introduction, the comparative studies on the morphological characters and propagation characteristics between P.lutea and P.lutea var.ludlowii have been carried out.The result shows that there are obvious differences in plant height, carpels number, colour of flowers, and the propagation between them; the comparative analysis of the karyotypes and the soluble protein subunits constituents were also carried out between P.lutea and P.lutea var.ludlowii, the result also shows there are differences between them.The simultaneous application of several indexes indicate that the P.lutea var.ludlowii should be upgraded as a species rank:P.ludlowii (Stern et Taylor) J.J.Li et D.Z.Chen, stat.nov.

Key words: Paeonia ludlowii, Taxonomic position, New rank