Characteristic species: Vascular - Pondweed, horned pondweed (Zannichellia palustris), ditch grass (Ruppia), wild celery, waterweed (Elodea), riverweed (Podostemum ceratophyllum), water lilies (Nymphea, Nuphar), floating-leaf pondweed (Potamogeton natans), and water shield (Brasenia schreberi), water smartweed (Polygonum amphibium). Floating Surface - Duckweeds (Lemna, Spirodela), water lettuce (Pista stratiotes), water hyacinth (Eichhornia crasspies), water nut (Trapa natans), water fern (Salvinia spp.), and mosquito ferns (Azolla). Floating Below Surface - Bladderworts (Utricularia), coontails (Ceratophyllum) and watermeals (Wolffia).