Eichhornia

Scientific name

Eichhornia Kunth.

Common names

water hyacinth, anchored water hyacinth

Family

Pontederiaceae

Similar genera

Heteranthera, Limnobium, Limnocharis, Monochoria, Pontederia

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 submersedsubmersed:
see submerged
leaves and elongate, anchored floating stem with large obovateobovate:
(adj) ovate, with the narrow end at the base
, erect leaves with slender petioles.

See Eichhornia azurea disseminule fact sheet.

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.

Habit

submersed, emergentemergent:
(adj) (syn. emersed) with parts raised out of the water; extending up out of the water
, anchored floating stem, or free floating stoloniferous rosetterosette:
(n) a radiating cluster of leaves, usually close to the ground at the base of a plant
plant

Brief description

Annual or perennialperennial:
(adj) (of a plant) having a life cycle of more than two years
. Stems floating, stoloniferous, or creeping, compact and rhizomatousrhizomatous:
(adj) possessing rhizomes
or elongate. Leaves submergedsubmerged:
(adj) (syn. submersed) under water; submerged below the water surface
, floating, or emergentemergent:
(adj) (syn. emersed) with parts raised out of the water; extending up out of the water
(or a combination of any two), in basalbasal:
(adj) at or pertaining to the base, or point of attachment
rosette or caulinecauline:
(adj) pertaining to or belonging to the stem
, alternatealternate:
(adj) (of leaves) bearing one leaf per node; placed singly on the stem at different heights
, distichousdistichous:
(adj) (of leaves or flowers) distinctly arranged in two ranks along an axis; leaves may be opposite or alternate
(2 rows), or spirally arranged, sessilesessile:
(adj) attached directly, without a stalk
or petiolatepetiolate:
(adj) relating to or in the form of a petiole; bearing petioles
, petiolepetiole:
(n) the stalk of a leaf
often inflatedinflated:
(adj) bladdery; swollen, or appearing so
with aerenchymaaerenchyma:
(n) plant tissue with large, gas-filled intercellular spaces that facilitates gaseous exchange and maintains buoyancy
in floating plants; submersedsubmersed:
see submerged
leaves linear, emersedemersed:
see emergent
leaves ovateovate:
(adj) egg-shaped in outline; generally with the broad end at or near the base
to orbicularorbicular:
(adj) circular in outline
, venationvenation:
(n) the arrangement of veins in a leaf
inconspicuous, parallel to palmatepalmate:
(adj) (of leaves or venation) with lobes, leaflets, divisions or veins originating from the same point
; base rounded to cordatecordate:
(adj) heart-shaped; in the form of two rounded lobes
; marginmargin:
(n) edge; rim
entireentire:
(adj) having a continuous margin that is not toothed or lobed
. Inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
a spikespike:
(n) an indeterminate, unbranching inflorescence of sessile flowers or flower clusters on a usually elongated axis
or paniclepanicle:
(n) an indeterminate, branched (often much-branched) inflorescence; the ultimate units may be of a different inflorescence type
, subtended by 2 reduced, dissimilar leaves (spathes); lower spathespathe:
(n) a large bract or bracts subtending and often enclosing an inflorescence
leaf-like, upper scale-like. Flower zygomorphiczygomorphic:
(adj) bilaterally symmetrical; symmetrical along only one plane
; perianthperianth:
(n) collective term for the calyx and corolla of a flower; also used for floral whorl(s) in which the calyx and corolla cannot be resolved; any of the leaves or bracts surrounding the sex organs of bryophytes
fused, of 6 showy tepals in 2 whorls of 3; lobes unequal, adaxialadaxial:
(adj) pertaining to the side facing toward the axis, as in the upper surface of a leaf
lobe larger than rest; tepals usually pink to purple with yellow spot on adaxialadaxial:
(adj) pertaining to the side facing toward the axis, as in the upper surface of a leaf
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.