The “floating” category of aquatic macrophytes includes free-floating and floating-leaved plants. Free-floating plants are not anchored in the sediment; they obtain their nutrients from the water. Florida’s native free-floating plants include the world’s smallest flowering plant (a duckweed called water meal, Wolffia columbiana); and two larger duckweeds,small duckweed (Lemna valdiviana) and giant duckweed (Spirodela polyrhiza). Other native free-floating plants are bladderwort (Utricularia spp.) and coontail (Ceratophyllum demersum).
The free-floating plant, water hyacinth (Eichhornia crassipes), is a non-native invasive plant in Florida and has been called “the worst aquatic weed in the world” by experts. In many Florida waters, it requires constant management, known as maintenance control to maintain low levels and keep waterways passable. Water hyacinth has invaded the waters of many countries from its native Brazil; and is profiled here. Salvinia (Salvinia spp.) and water lettuce (Pistia stratiotes) are also non-native invasives that form dense mats covering the water surface.
Floating-leaved plants typically are rooted in the sediments and have leaves that float on the water surface. Water lilies (Nymphaea spp.), spatterdock (Nuphar lutea subsp. advena), American lotus (Nelumbo lutea), and water shield (Brasenia schreberi) are examples of floating-leaved plants. They generally grow along the shoreline, lakeward of the emersed plants.
Floating and floating-leaved plants occur in many Florida waterbodies. Rooted floating-leaved plants can grow completely across shallow waterbodies. The roots of floating-leaved plants provide a stable surface for successful fish spawning.