Water-hyacinth: Eichhornia crassipes
Water-hyacinth is a floating plant that has clusters of leaves
with spongy stalks arising from a base of dark purple feathery
roots. The leaf clusters are often linked by smooth horizontal
stems (called stolons). Linked plants form dense rafts in the water
Look for first
- Large spike of lavender-blue flowers
- Spongy, bulbous leaf stalks
- Large rounded glossy leaves
||Leaves: leaves formed in rosettes; petioles to 30cm (12 in) or
more, spongy, usually inflated or bulbous, especially near the
base; leaf blades roundish or broadly elliptic; glossy green to
15cm (6 in) wide.
||Flowers: single spike of several (8 to 15) showy flowers above
rosette, to 30cm (12 in) long. Flowers lavender-blue with a
yellow blotch, to 5cm (2 in) wide, somewhat 2-lipped; 6 petals, 6
||Fruit: 3-celled capsule with many minute, ribbed seeds; seeds
form in submerged, withered flowers.
This native of South America is now considered a
major weed species in more than 50 countries. The floating
water-hyacinth was introduced into Florida in the 1880s and covered
more than 120,000 acres of public lakes and navigable rivers by the
early 1960s. Since then, intensive management efforts coordinated
by the Florida Department of Environmental Protection and the U.S.
Army Corps of Engineers have reduced water hyacinth to
approximately 2,000 acres statewide.
Origin in tropical Brazil, but has become naturalized in many
warm parts of the world: Central America, North America, Africa,
India, Asia, Australia, and New Zealand.
Because of its aggressive growth rate,
water-hyacinth is illegal to possess in Florida without a special
The growth rate of water-hyacinth is among the highest of any
known plant. In Florida, water-hyacinth populations can
double their size in as little as 2 weeks by sending off short
runner stems that develop new plants (daughter plants).
Water-hyacinth also has the ability to reproduce by seeds.
Why water-hyacinth must be managed
Water-hyacinth blocks waterways and limits boat traffic,
recreation, flood control and wildlife use. By producing a dense
canopy at the water surface, this exotic pest plant shades out
native submersed plant species and can uproot native emergent
species that are important to wildlife.
Environmental damage caused by water-hyacinth populations
- Water-hyacinth mats lower dissolvedoxygen concentrations,
damaging fish populations.
- One acre of water-hyacinth can yearly deposit as much as 500
tons of rotting plant material on the bottom of a waterway.
- Water-hyacinth mats can increase flooding in rivers and canals
by forming dams.
- Water-hyacinth mats provide ideal breeding environments for
- Water-hyacinth populations decrease biodiversity in
Image Credit: Center for Aquatic and Invasive Plants, University of Florida