Five leaf traits were analyzed in different plant species in an aquatic-terrestrial ecotone, Li River, to investigate differences in these traits between different types of functional plants in severe and mild inundation zones, and to explore the physiological responses of plants suffering from long-term submergence stress. By analyzing the relationships between leaf traits in plants subjected to severe inundation, differences between the results of this study and those on the global scale are also discussed. The five leaf traits analyzed were:leaf mass per area (LMA), leaf maximum net photosynthesis rate (A_max), leaf nitrogen content per mass (N_mass), leaf phosphorus content per mass (P_mass), and leaf potassium content per mass (K_mass). The results were as follows:(1) The values of A_mass, N_mass, and P_mass under severe submergence were significantly higher than those under mild submergence. (2) The LMA value for grasses was relatively lower than that for trees and shrubs, whereas A_max and PNUE (photosynthetic nitrogen use efficiency) were higher for grasses. (3) The N_mass, P_mass, and PNUE values for grasses in the severe inundation zone were significantly higher than those in the mild inundation zone, while there were no significant differences in leaf traits for trees and shrubs between the two zones. (4) The relationships between leaf traits in the severe inundation zone were similar to those on the global scale, and the species in the severe inundation zone had lower LMA, higher A_mass, N_mass, and P_mass. These results suggest that improving photosynthetic capacity and increasing the levels of relevant leaf nutrients may be involved in the adaptation of plants to aquatic-terrestrial ecotone conditions. Compared with trees and shrubs, grasses showed stronger adaptability to submergence, which illustrates the differences in adaptability between different types of functional plants. The results of this study indicate that a spectrum of leaf economics also exists in plant species in the severe inundation zone, and that these represent species with a fast investment-return on the leaf economic spectrum.