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
Morphology
• 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).
Morphology
• Flowers have 6
purple to blue to
lavender petals with
the upper ones
having a yellow,
blue bordered
central spots.
Taxonomy
Division: Magnoliophyta
Class: Lilopsida
Subclass: Commelinidae
Order: Pontederiales
Family: Pontederiaceae
Genus: Eichhornia crassipes
Not a member of the True Hyacinth family
More closely related to native pickerelweed
Reproduction
• 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 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 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.
Control
• Mechanical
– May be picked from water.
– Specialized machines are used to harvest
from colonized waters.
• Biological Control
– There are many natural predators of
waterhyacinth.
Control
• 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.
Control
• 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/danoffburg/invasion_bio/inv_spp_summ/water%2525
20hyacinth.html