Pontederia (=Eichornia) crassipes (Floating Water Hyacinth) is a large floating aquatic plant with beautiful flowers, native to South America, but widely introduced to tropical and warm-temperate regions around the world. The plant has dangling roots, about 800-1,000 m long, and a rhizome,10-300 mm tall; from which grow purplish stolons. Some of the petioles (leaf-stalks) leaves develop inflated floats, ending in heart-shaped leaves,. A cluster of 6-10 large, purple six-petaled flowers grows on a spike above the rhizome. The whole plant rises up to 1000 mm above the water. The stolons of the plant easily, break, and the broken clusters develop into new plants, so that this plant can rapidly reproduce asexually, creating massive dense floating mats. At the same time, the pollinated flowers produce large quantities of seeds The mats can block out light reaching the bottom, and can be dense enough to support a dog or child. The mats can obstruct navigation, interfere with water flows, favor mosquitos, and decrease habitat value for fish, birds, and other species.t is a competitor with the native floating plant, Water Pennywort (Hydrocotyle umbellata), and has replaced it in some areas.
Water Hyacinths may have been introduced to North America at an exhibition in New Orleans in 1884 In estuaries, Floating Water Hyacinths are abundant in tidal fresh waters but limited, to salinities below 5 PSU. In 1896, they became abundant enough to obstruct navigation on the St. Johns River. Florida. They were introduced to the Sacramento River by 1904, and reached the Delta by the 1940s. Control programs started in the 1950s, and in 1983, biocontrol insects were introduced, withlittle or no success. Water Hyacinths are abundant in the freshwater regions of estuaries in Atlantic Florida, the Gulf states, and the Sacramento-San Joaquin Delta. Control of Water Hyacinths for navigation, aesthetic, and habitat values had involved mechanical mowing, herbicides, and biocontrol. Four species of insects (Chevroned Water-Hyacinth Weevil: Neochetina bruchi); N. eichorniae: Mottled Water-Hyacinth Weevil; (Niphograpta (=Sameodes) albiguttalis Water Hyacinth Moth Megamalus scutellaris: Water Hyacinth Planthopper) have been introduced in Florida, the Gulf States, and the Delta. In Florida, and the Gulf states, biocontrol has been moderately successful, reducing the need for mechanical and chemical control In the San Francisco Bay Delta, only the Chevroned Water-Hyacinth Weevil: became established, but in numbers too small to affect Water Hyacinth biomass. Water hyacinth has provided habitat for 3 non-native crustaceans, the amphipod Crangonyx floridanus and the isopods Caecidotea racovitzai and Asellus hilgendorfii in the Delta.