Skip to main content
Invasive Species: Water Chestnut

Invasive Species: Water Chestnut

Water Chestnut

(Trapa natans)
*Not detected in Michigan*

WATCH LIST - PROHIBITED IN MICHIGAN

Report this species to:

EGLE Aquatic Invasive Species Program EGLE-WRD-AIP@Michigan.gov.

If possible, please take one or more photos of the invasive species you are reporting. Also make note of the location, date and time of the observation. This will aid in verification of your report. You may be asked to provide your name and contact information if follow-up is needed.

- Or - use the Midwest Invasive Species Information Network (MISIN) online reporting tool

- Or - download the MISIN smartphone app and report from your phone - MISIN.MSU.edu/tools/apps/#home

Identification:

  • Green, floating leaves with sharply serrated edges.
  • Leaves form a densely crowded rosette.
  • Small, white 4-petaled flowers.
  • Produce a hard “woody” nut surrounded by sharp barbed spines.

water chestnut
Water chestnut's serrated leaves float on the water (Michigan DNR). 

water chestnut with seed
Water chestnut with seed. Leslie J. Mehrhoff, University of Connecticut, Bugwood.org. 

water chestnut cluster
Water chestnut cluster. Leslie J. Mehrhoff, University of Connecticut, Bugwood.org. 

Habitat: While water chestnut shows a preference for shallow, nutrient-rich lakes and rivers, it can grow in mucky substrate

Native Range: Europe, Asia and Africa.

U.S. Distribution: Naturalized in the northeastern United States.

Local Concern: Water chestnut forms dense mats that shade out native aquatic vegetation, leading to a decrease in biodiversity. Decomposition of vegetation below a dense mat decreases oxygen levels and can cause fish kills. Boating and other recreational activities become almost impossible in an area invaded by water chestnut.

Other Common Names: European water chestnut, horned water chestnut, water caltrop.

MORE INFORMATION:

Water Chestnut Invasive Species Alert - Printable PDF

MDARD Weed Risk Assessment for Water Chestnut (Trapa natans) - This document evaluates the invasive potential of the plant species using information based on establishment, spread and potential to cause harm.