The wetland plants that will work are trees like birch and alder and shrubby plants such as red twig and yellow twig dogwood plus skunk cabbage, gunnera, primroses of the candelabra variety as well as various ferns. Your best bet is to observe the native plants growing in wetlands in your area and try to use these same plants in your marshy space. Native plants will be best for persevering the water quality and providing habitat for the native birds and insects that depend on wet lands. Keep growing, Marianne Binetti