Considering the heightened vulnerability of tidal marshes to SLR, an increasing number of studies are examining flooding and other climate change impacts to marsh plant growth and viability and their feedbacks to marsh elevation and resilience. As the authors note, most of these do not consider responses of different genotypes of the same species, but rather responses at the species level or among species. Thus, this experiment, which investigated biomass responses of different plant genotypes to increasing flooding frequency, fills an important gap. While the overall conclusion that the low-marsh genotype is better adapted to flooding than the high-marsh genotype is an intuitive one, this paper provides some direct evidence of biomass responses and suggests that formation of longer rhizomes by the low-marsh genotype serves as a