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W2O!: Water Chestnut



Water Chestnut (Trapa natans)


Water Chestnut.  Robert Johnson, Cornell University.  Ruthanna Hawkins, Cayuga Lake Watershed Network.  Used with permission.
Water Chestnut. Robert Johnson, Cornell University. Ruthanna Hawkins, Cayuga Lake Watershed Network. Used with permission.
Water Chestnut Drawing, University of Florida, Center for Aquatic and Invasive Plants Line Drawing DVD Master.  Used with permission.
Water Chestnut Drawing, University of Florida, Center for Aquatic and Invasive Plants Line Drawing DVD Master. Used with permission.
  • Native to Asia
  • Introduced into NY in late 1800s
  • Plant Characteristics
    • Submersed, rooted and floating annual plant that forms dense mats of floating "rosettes"

      Water Chestnut Infestation in Seneca River, Kelly Fallone, CCE
      Water Chestnut Infestation in Seneca River, Kelly Fallone, CCE


    • Floating leaves are triangular with "toothed" edges and are waxy on the top and hairy on the underside
    • Water Chestnut Plant, Kelly Fallone, CCESmall white flowers with four petals can bloom late June through September
    • Produces thorny four pointed nutlettes in early summer
    • Reproduces from the 100+ new seeds in each nutlet
    • Can grow up to 16 feet long
    • Inhabits lakes, ponds and slow moving waters.
    • It is currently in the Hudson and Mohawk Rivers, Lake Champlain, Lake Ontario-Sodus Bay, Seneca and Oswego Rivers, Oneida Lake and Rivers, Lake George and others. 


Map of Water Chestnut Infestation, USGS, Nonindigenous Aquatic Species
Map of Water Chestnut Infestation, USGS, Nonindigenous Aquatic Species

Water Chestnut, Photo by Kelly Fallone, Cornell Cooperative Extension of Cayuga County
Water Chestnut, Photo by Kelly Fallone, Cornell Cooperative Extension of Cayuga County

The invasive water chestnut differs from the Chinese water chestnut eaten the U.S. The image to the right shows the sharp, hard spines of the invader. The image on the left shows unpeeled, rounded tuber of the Chinese Water Chestnut, which is produced at the base of a grass-like plant. In south east Asia, both plants that bear the name water chestnut are raised for food.
Chinese Water Chestnut Water Chestnut Nutlette, Kelly Fallone, CCE
Chinese Water Chestnut Invasive Water Chestnut


The following is a document about water chestnut. Water Chestnut Alert (PDF)

Water Chestnut Look Alikes

Native Look Alike:  Spatterdock (Nuphar spp.)

Spatterdock Drawing, University of Florida, Center for Aquatic and Invasive Plants Line Drawing DVD Master.  Used with permission.
Spatterdock Drawing, University of Florida, Center for Aquatic and Invasive Plants Line Drawing DVD Master. Used with permission.
  • Plant Characteristics
    • Heart shaped leaves up to 16 inches long
    • Parallel or overlapping rounded lobes
    • Yellow flowers
    • Large mid-rib
    • Found in ponds or slow moving waters
Native Look Alike: Water Lily (Nymphaea spp.)
Waterlilies, Kelly E. Somerlot, Onondaga County CCE
Waterlilies, Kelly E. Somerlot, Onondaga County CCE
Water Lily Drawing, University of Florida, Center for Aquatic and Invasive Plants Line Drawing DVD Master.  Used with permission.
Water Lily Drawing, University of Florida, Center for Aquatic and Invasive Plants Line Drawing DVD Master. Used with permission.
Plant Characteristics
  • Round leaves with pointed lobes, 6-8 inches in length
  • Many petalled white flowers float on water surface
  • Veins on leaf radiate out from where leaf and stem meet
  • Found on quiet waters