Waterhyacinth
Eichhornia crassipes

Origin: Amazon basin

Background
Water hyacinth is one of the worst weeds in the world--aquatic or terrestrial. It took 100 years to place water hyacinth under "maintenance control" after it was introduced into the U.S. Thanks to research and the diligence of field workers using herbicides, machines, and introduced insects, this plant in the U.S. now rarely forms the huge floating infestations of the recent past. Unfortunately, this is not true in many other places in the world, where water hyacinth continues to present daunting environmental and economic problems.

Description
Rhizomatous, floating aquatic herb with feathery roots; leaf blades ovate to orbicular, petioles much-inflated at base; flowers large and showy, perianth segments entire, violet, upper lobe with yellow-centered blue patch.