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Last Updated: Spring 2012
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Synonyms: Eichhornia speciosa Kunth
Piaropus crassipes (Mart.) Raf.

Family: Pontederiaceae

Home Range/U.S. Introduction:
Eichhornia crassipes (Mart.) Solms. is native to South America, probably Brazil. Plants are thought to have been first introduced into the United States at the 1884 Cotton States Exposition in New Orleans, Louisiana (Sculthorpe 1967). Because of its showy flowers, waterhyacinth is sold as an ornamental for small fish ponds and sometimes escapes or is intentionally introduced into larger water bodies such as lakes and reservoirs. The distribution of E. crassipes shown on the map in this system depicts where populations are expected to "overwinter" and regrow during most years.

Another species of waterhyacinth, Eichhornia azurea (Sw.) Kunth, has been introduced into south Texas from Latin America (Correll and Johnson 1970, Tarver et al. 1986). It can be distinguished from E. crassipes by a lack of inflated petioles and the presence of an obvious stem with leaves along its entire length that are separated by distinct internodes.

U.S. Range Map:

Distribution was determined by a combining of the distribution information obtained from the following websites:

USDA, NRCS. 2012. The PLANTS Database (http://plants.usda.gov, 18 June 2012). National Plant Data Team, Greensboro, NC 27401-4901 USA.

U.S. Geological Survey. [2012]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/18/2012].

Species Description:
Water-hyacinth floats on the surface of the water or is sometimes stranded on mud and appears rooted. The individual plants consist of several leaves in rosettes and are connected by stolons. Prominent, black roots hang from each rosette. The leaf petiole is usually inflated, spongy, and up to 20 cm long. The leaf blades are thickened, leathery, 2 to 15 cm long and 2 to 10 cm wide, suborbicular, ovate or broadly elliptic with parallel veins. The leaf bases are heart-shaped, square or rounded, the leaf apices rounded to flattened. The inflorescence is a spike with several light-blue to bluish-purple flowers that have a yellow blotch. The fruit is a many seeded capsule.

Habitat/Growth Characteristics:
Waterhyacinth grows in ponds, canals, freshwater and coastal marshes, lakes, and back water sloughs and oxbows along rivers. Reproduction is primarily by vegetative means from runners or stolons. This method of vegetative reproduction allows the plant to quickly colonize large areas in relatively short periods of time. During periods of drought, waterhyacinth can survive as seed that remain dormant until reflooding occurs. Because waterhyacinth is free-floating, wind and water currents function to distribute plants within a water body (Tarver et al. 1986). The large, robust plants of waterhyacinth are often referred to a "bull hyacinths". Populations of waterhyacinth are dramatically influenced by climatic conditions, expanding during years with mild winters and contracting or being eliminated from areas of the interior United States during particularly harsh winters.

Dense growth of waterhyacinth can clog canals and water intakes and restrict navigation along rivers and lakes. It can also negatively impact water quality and exclude native vegetation. Problems caused by this species far outweigh any benefits it provides in natural aquatic and wetland habitats.

Correll, D. S. and M. C. Johnston. 1970. Manual of the Vascular Plants of Texas Research Foundation, Renner, Texas.Sculthorpe, C. D. 1967. The Biology of Aquatic Vascular Plants. St. Martin’s Press, New York.

Tarver, D. P., J. A. Rogers, M. J. Mahler, and R. L. Lazor. 1986. Aquatic and Wetland Plants of Florida. Third Edition. Florida Department of Natural Resources, Tallahassee, Florida.