Water Chestnut   (Trapa natans)

DESCRIPTION

Water Chestnut (Trapa natans) is an aquatic plant that is found in slow moving nutrient filled waters such as ponds, lakes, and shallow streams.  The plant's size although characteristically small, may have branching stems reaching lengths of 16 feet.  Leaves from this plant are both surfaced and submerged; Surface leaves are triangular in shape with long petioles which have an inflated spongy region (air bladder) while the submerged leaves are opposite and contain numerous adventitious roots.  Water chestnuts begin to flower in mid to late July, with their nuts ripening approximately one month later. Flowering and seed production continue into the fall when frost kills the floating rosettes. The mature nuts sink to the bottom when dropped and may be able to produce new plants for up to 12 years. The plant spreads either by the rosettes detaching from their stems and floating to another area, or more often by the nuts being swept by currents or waves to other parts of the lake or river. The plant overwinters entirely by seed. Water chestnut is a nuisance aquatic plant that limits boating and fishing in infested areas. It has the potential to infest wetlands and critical environmental habitats in other areas of the state.

(Source: 1. Vermont Agency of Natural Resources, Department of Environmental Conservation, http://www.anr.state.vt.us/dec/waterq/ans/wcpage.htm; 2. Water Chestnut: Environmental Fact Sheet, New Hampshire Department of Environmental Service, http://www.des.state.nh.us/factsheets/bb/bb-43.htm)

IMPACTS

Water Chestnut is an extremely high competitor in slow moving shallow water, with semi-permeable mud bottoms.  Once established, this plant will spread rapidly and control large surface areas leaving no room for native aquatic plants. Rapid sedimentation may occur in water chestnut areas due to trapping of silt. The reduction of light penetration and the resulting loss of oxygen, proves a hazard to fish and other aquatic species, and the Water Chestnut is a poor source of food for wild fowl.  Seeds can cause painful injury when stepped on. 

In addition, impacts on recreation may be seen in areas where the plant is dominate due to its reduction in available fishing area and its hazard to boating motors. Infestations can make boating, fishing and swimming difficult or impossible. The expense of controlling this plant is large, with numbers reaching well into the millions of dollars for both states and federal agencies.  

(Source: 1. Vermont Agency of Natural Resources, Department of Environmental Conservation, http://www.anr.state.vt.us/dec/waterq/ans/wcpage.htm; 2. Water Chestnut: NY-Invasive Plant Council of New York State,  http://www.ipcnys.org/ipc_twentytn.html)

(Source: 1. Water Chestnut in Maryland, Chesapeake Bay, http://www.dnr.state.md.us/bay/sav/water_chestnut.html)

(source: 1. Water Chestnut in Maryland, Chesapeake Bay, http://www.dnr.state.md.us/bay/sav/water_chestnut.html); 2. Water Chestnut Eradication, Mystic River Watershed Association, http://www.tufts.edu/mystic/invasives/wc2001.htm)

Water Chestnut (Trapa natans L.): Plant profiles, Natural Resource Conservation Service
    http://plants.usda.gov/cgi_bin/plant_profile.cgi?symbol=TRNA
This site includes distribution, links, wetlands indicator, and status introduced information.

2001 Year Water Chestnut Harvest Report
    http://www.tufts.edu/mystic/invasives/wc2001.htm

Water Chestnut: Environmental Fact Sheet, New Hampshire Department of Environmental Service
    http://www.des.state.nh.us/factsheets/bb/bb-43.htm
This fact sheet explains a brief information on water chestnut found in New Hampshire.
   
Water Chestnut: NY-Invasive Plant Council of New York State-Top 20
    http://www.ipcnys.org/ipc_twentytn.html

This site includes a description of biology, habitat, range in New York, origin, spread, and problem. 

USGS Nonindigenous Aquatic Species: Water Chestnut
    http://nas.er.usgs.gov/plants/docs/tr_natan.htm
This page explains water chestnut U.S. range with a figure.

Water Chestnut: Chesapeake Bay
    http://www.dnr.state.md.us/bay/sav/water_chestnut.html
This site contains general fact of water chestnut, and their removal efforts: 1999 - 2001 Water Chestnut Removal Report;  2001 Removal Effort;  2000 Removal Effort;  1999 Removal Effort.

Water Chestnut Appetizer: About (Chinese Cuisine)
    http://chinesefood.about.com/library/blrecipe045.htm 

Cashew Shrimp with Water Chestnuts: Food Network   
    http://www.foodtv.com/foodtv/recipe/0,6255,17944,00.html