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Photo by: Gary Fewless

Location: UWGB, Brown Co., WI

Date taken: Sep 6, 2001

Camera: Olympus CL 2500L digital camera


Water hyacinth invades the Cofrin Arboretum!

Water Hyacinth (Eichhornia crassipes)

Click here to see close-up.

A visitor to UW-Green Bay's Cofrin Arboretum reported Water Hyacinth in one of the Arboretum's ponds. I was highly sceptical of the report, but a quick check demonstrated its accuracy. This species is native to Brazil and is now a costly and troublesome invasive aquatic species where it has been introduced to the U.S. It normally grows "wild" only in the southern tier of states from Texas to Florida and Georgia and north along the Atlantic coast to North Carolina. It has been reported from farther north where it is planted in ponds as a decorative species, but plants do not survive winter there. It was, therefore surprizing to find it thriving in northern Wisconsin.

Water hyacinth is an aquatic species and floats on the surface of the water, where it quickly reproduces vegetatively by stolons to cover large areas of the open water. In dense populations it can shade out competing native plants, contributes large quantities of decaying biomass to the water body and can interfere with the exchange of oxygen from the air into the water column, thereby drastically decreasing water quality and severely changing the organisms that can survive there. It is considered a Federally noxious weed in the U.S. and is believed to essentially cover at least 125,000 acres of water in the southeastern states. It is thought to have been first introduced to the U.S. in 1884 in Louisiana, where it escaped after it was intentionally imported for an "exposition".

Water hyacinth is in the same family (Pontederiaceae )as our native Pickerel Weed (Pontederia cordata). The inflated petioles help the plants to float and the dense root systems hang down into the water where they can absorb nutrients.

The tendency to intentionally release alien species into our environment has been extremely expensive and has caused great harm to our native communities and species. When alien species are highly successful in a new location they quickly occupy habitats which are then no longer available to native species. The result is often a decrease in biodiversity and may contribute to the rarity of native species. Please consider the possible consequences and do not release exotic species into the wild, even if you find then attractive or otherwise desirable. Invasive species, many of them intentionally introduced, are believed to cost U.S. citizens billions of dollars each year due to their impacts on agricultural and natural ecosystems.

© 2001-2004 The Cofrin Center for Biodiversity and the University of Wisconsin Green Bay, All Rights Reserved
Last updated on April 15, 2014