Abstract: Photosynthetic characteristics of Saururus chinensis and Houttuynia cordata, two Chinese traditional medicines of Saururaceae, were studied to determine their favorable cultivation conditions. Photosynthetic activity of them were assessed via measuring light response curves, CO2 response curves, diurnal changes of photosynthesis, chlorophyll fluorescence parameters and chlorophyll (Chl) content. The results showed that S. chinensis and H. cordata were both shade-tolerant species, their light compensation points (LCP) were 2.93 and 1.63 μmol·m-2·s-1 respectively. Compared with H.cordata, S. chinensis had higher LCP and light saturation point (LSP) and lower CO2 compensation point (CCP) and CO2 saturation point (CSP). Diurnal variation of net photosynthetic rate (Pn), transpiration rate (E) and stomatal conductance (Gs) of these two species presented two\|peak curves. S. chinensis also showed higher chlorophyll content and higher values of chlorophyll fluorescence parameters in high light intensity than H. cordata. Compared with H. cordata, S. chinensis was obviously higher in photosynthetic capacity, and showed a well acclimation in habitat of high light intensity. Therefore, its necessary to choose a much shadier habitat for H. cordata when planted．

Key words: Saururus chinensis, Houttuynia cordata, light response curves, CO2 response curves, photosynthesis chlorophyll fluorescence