Wetland plant ID please

Wetland plant ID please

Observation - Wetland plant ID please. Description: Leaves like a dock, but not as tough, more the texture of an impatiens. Hollow stems, I believe. Dark green on both sides, not shiny.

Leaves like a dock, but not as tough, more the texture of an impatiens. Hollow stems, I believe. Dark green on both sides, not shiny.