Scientific name
Eichhornia Kunth.
Common names
water hyacinth, anchored water hyacinth
Family
Pontederiaceae
Native distribution
tropical America, Africa
Species cultivated
Eichhornia azurea (Sw.) Kunth
E. crassipes (Mart.) Solms
E. diversifolia (Vahl) Urb.
E. heterosperma AlexanderE. natans (P. Beauvois) Solms
E. paniculata (Spreng.) Solms
U.S. Federal Noxious Weed: Eichhornia azurea
Identification: Eichhornia azurea can be distinguished from other Eichhornia by its elongate, fan-like submersed leaves and elongate, anchored floating stem with large obovate, erect leaves with slender petioles.
Adventive distribution
Eichhornia crassipes is introduced into numerous tropical and subtropical countries around the world. Eichhornia paniculata, E. diversifolia and E. azurea have historical records in Texas and Florida, but apparently no extant populations have been substantiated recently in the United States.
Weed status
Eichhornia azurea (Sw.) Kunth is a major aquatic weed in some countries and an aquatic weed on the U.S. federal noxious weed list.
E. crassipes (Mart.) Solms is considered one of the world's most serious aquatic weeds and is declared an aquatic noxious weed in many countries.
Due to the weed status of E. crassipes and E. azurea, several, and in some cases, all species of Eichhornia have been subsequently designated as prohibited imports in various countries.
Brief description
Annual or perennial. Stems floating, stoloniferous, or creeping, compact and rhizomatous or elongate. Leaves submerged, floating, or emergent (or a combination of any two), in basal rosette or cauline, alternate, distichous (2 rows), or spirally arranged, sessile or petiolate, petiole often inflated with aerenchyma in floating plants; submersed leaves linear, emersed leaves ovate to orbicular, venation inconspicuous, parallel to palmate; base rounded to cordate; margin entire. Inflorescence a spike or panicle, subtended by 2 reduced, dissimilar leaves (spathes); lower spathe leaf-like, upper scale-like. Flower zygomorphic; perianth fused, of 6 showy tepals in 2 whorls of 3; lobes unequal, adaxial lobe larger than rest; tepals usually pink to purple with yellow spot on adaxial lobe. Dispersal by numerous seeds or stem fragments; seeds of E. crassipes may be viable in the sediment for 15 years.
Natural habitat
all types of slow flowing or still water bodies
Additional comments
Eichhornia contains six species, of which five are presently cultivated for aquaria or ponds, and one, E. paniculata, is often a research subject in flower structure genetics.
