american frogbit: American plant with roundish heart-shaped or kidney-shaped leaves; usually rooted in muddy bottoms of ponds and ditches
aquatic plant: a plant that grows partly or wholly in water whether rooted in the mud, as a lotus, or floating without anchorage, as the water hyacinth
nuisance: (law) a broad legal concept including anything that disturbs the reasonable use of your property or endangers life and health or is offensive