Abstract: By using the method of anatomy, we compared and analyzed the anatomical characterstics of the leaf and stem of five wild populations of Huperzia serrata in Xiangxi Region. The results showed that H.serrata populations have obvious differences in anatomical characterstics. Among all anatomical characterstics, vascular cylinder thickness, cortex thickness, spongy tissue thickness, and leaf thickness are the main factors which contribute to the differences of anatomical characterstics of H.serrata populations; The anatomical characterstics of stem and leaf are morphologically adaptive to damp environment, but among all populations, H.serrata in S1 population have the tendency of adapting dry environment. These morphological characterstics are mainly controlled by genetic factors, but environmental factors(mainly light and water) also have important influence on them. Therefore, the anotomical difference and plasticity of H.serrata populations are essential for the adaptation and the existance of H.serrata.

Key words: Huperzia serrata, Xiangxi Region, anatomical characterstics of leaf and stem, ecological adaptation