Abstract: Phenotypic plasticity, a crucial plant evolutionary strategy, enables rapid adaptation to environmental changes, and can even affect subsequent generations via transgenerational plasticity. Thus, parental effects can profoundly influence offspring phenotypes, and the environment can mediate such parental effects. Global climate change has increased the frequency of flooding, but research on the impact of flooding on parental effects remains limited. Therefore, this study examined how flooding affects the phenotypic and physiological characteristics of parents and, subsequently, the offspring through parental effects. This study modeled the effects of two natural habitats (flooding vs. no flooding) on four generations of the clonal plant Hydrocotyle vulgaris. Flooding was observed to have a positive impact on the biomass of roots, stems, and leaves, as well as the specific leaf areas of H. vulgaris parents and offspring. The offspring environment affected the manifestation of flooding-induced parental effects. Growth was favored when both parents and offspring experienced flooding, facilitating faster adaptive responses to similar environments, especially in stems and leaves. These parental effects can persist for at least three generations and may accumulate in consistently flooded offspring. These findings provide a scientific basis for studying phenotypic plasticity and parental effects in clonal plants.

Key words: clonal plants, flooding, phenotypic plasticity, parental effects, multigenerational