Abstract:Flooding induced the changes in net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of 17-month-old seedlings of Cleistocalyx operculatus. Pn, Gs and Tr began to decline progressively after 5 days of flooding. However, a few seedlings which developed adventitious roots (AR) on submerged portion of the stem starting on the 35th day of flooding showed a gradual increase in Pn, Gs and Tr, and maintained a higher level of Pn, Gs and Tr by the 80th day of flooding. The daily courses of Pn，Gs and Tr of seedlings with AR showed a pattern of two peaks，and the regression analysis indicated that Pn was positively correlated with Gs (r=0.69,p<0.05)．