Abstract: Remnant populations of Myricaria laxiflora (Franch.) P. Y. Zhang & Y. J. Zhang undergo an annual cycle of post-flood recovery following prolonged submergence during summer flooding. Focusing on populations inhabiting Guanzhou Island in Zhijiang City, this study examined leaf functional traits and photosynthetic physiological parameters across four distinct age groups to elucidate age-dependent recovery strategies post-summer flooding. Results revealed pronounced age-related variation in both branch and leaf functional traits. Mid-aged individuals (groupⅢ) exhibited the most robust vegetative recovery, characterized by maximal primary and secondary branch elongation, as well as elevated leaf number, surface area, dry weight, and specific leaf area, followed by young (groupⅡ), old (groupⅣ), and very young (groupⅠ) populations. The growth patterns of branch and leaf functional traits varied considerably across age groups during recovery, leading to differentiation of these traits among groups. Photosynthetic physiology also varied significantly among age groups during recovery. Overall photosynthetic performance, light response parameters, and photosynthetic pigment content decreased progressively with increasing age, with the youngest (groupⅠ) population exhibiting the best performance, followed by the young (groupⅡ), mid-aged (groupⅢ), and old (groupⅣ) populations. Photosynthetic physiology varied dynamically throughout the recovery growth period and was partially suppressed during the mid-recovery phase due to suboptimal low temperatures.