n submersed plant with whorled lanceolate leaves and solitary axillary flowers; Old World plant naturalized in southern United States and clogging Florida's waterways
Syn|Hyper
hydrilla
aquatic plant, hydrophyte, hydrophytic plant, water 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