Which plant am I?

I live in the wet, marshy areas of the dune and wetland area. My thick roots (rhizomes) and seeds are important food for wildlife such as geese and muskrats. Lately I've been having trouble with two pests from Europe: reed grass and purple loosestrife. Both are trying to take over my marsh and don't provide any food for wildlife.

Water-lily

Water chestnut

Cattail