Water hyacinth : Either of several tropical aquatic plants of the genus Eichhornia, related to the pickerel weed.

Example:


Taxonomy
water hyacinth, Lake Victoria, plant, Eichhornia crassipes, Common Water, species, unranked, nutrients, United Nations News, weed, Environmental Management Project, free encyclopedia, West Africa, lakes, hyacinth, Opande, seven species, Food and Agriculture Organization of the United Nations.

Defination from the web:
water hyacinth may be mistaken for frog's-bit (Limnobium spongia). One of the fastest growing plants known, water hyacinth reproduces primarily by way of runners or stolons, which eventually form daughter plants. ...