Waterhyacinth

By Jason Zarnowski

Eichhornia crassipes

• Introduced from South America in the 1880’s as an ornamental plant.

• Now invades Asia, Africa, as well as North and South America.

North American Distribution

MorphologyMorphology• Leaves broadly ovate

and circular, 4-8 inches in diameter with numerous longitudinal veins.

• Leaves grow in whorls.• Leaf stalks are bulbous

and spongy.• Flowers grow on stalk

20 inches tall with spike of numerous, showy flowers (8-15).

MorphologyMorphology• Flowers have 6

purple to blue to lavender petals with the upper ones having a yellow, blue bordered central spots.

TaxonomyTaxonomyDivision: Magnoliophyta

Class: LilopsidaSubclass: CommelinidaeOrder: Pontederiales

Family: Pontederiaceae Genus: Eichhornia crassipes

Not a member of the True Hyacinth familyMore closely related to native pickerelweed

ReproductionReproduction• Sexual reproduction produces

numerous seeds.– Each inflorescence can produce 3,000

seeds that can remain viable for 15-20 years.

• Most reproduction is vegetative. – Reproduces rapidly from rhizomes,

offsets, and tubers to form dense mat, sometimes dense enough to walk on.

Ecological ImpactEcological Impact• Dense mats reduce light penetration to

other aquatic biota.• Reduce the amount of dissolved oxygen in

the water.– Changes invertebrate community, which affects

fish.• Decaying plants causes spike in nutrients,

also causing spike in algal blooms also leading to reduced dissolved oxygen and light penetration.

Economic ImpactsEconomic Impacts• Chokes off flow of water.

– Access to shore restricted.– Transportation through water way also restricted.– Reduced flow means less available water for

irrigation.– Clogs irrigation pumps.

• Impacts mosquito control by hindering insecticide application and provides habitat for breeding insects.– Reduced water circulation.

ControlControl• Mechanical

– May be picked from water.– Specialized machines are used to harvest

from colonized waters.• Biological Control

– There are many natural predators of waterhyacinth.

ControlControl• Biological Control (cont.)

– Four insects are commonly used:• Neochetina eichhorniae (weevil)• N. bruchi (weevil)• Niphograpta albiguttalis (moth)• Orthgalumn terebrantis (mite)

• Healthy plant community must be established in order to establish control communities.

ControlControl• Suppression may take many years.

– Methods are being tested to use combination of mechanical, biological and herbicidal (diquat) methods to make control more expedient.

• Control can be very successful.

Works Cited• Driesche, R. V., Blossey, B., & Hoddle, M. (2002).

Water Hyacinth. In . Mark (Ed.), Biological Control of Invasive Plants in the Eastern

United States (pp. 41-64). : USDA Forest Service.

• Osei-Agyemang, M. (2003). Introduced Species Summary Project Water Hyacinth

(Eichhorinia crassipies). Retrieved Sep. 13, 2008, from http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/water%252520hyacinth.html