 |
|
|
||||
| NAS - Nonindigenous Aquatic Species |
Translate this page with 
Common Name: water-chestnut
Synonyms and Other Names: water chestnut, horned water chestnut, water caltrop
Taxonomy: available through 
Identification:
The European water chestnut is a rooted aquatic plant with submersed and floating leaves. The feathery submersed leaves form whorls around the stem; the 3/4 to 1 ½ inch glossy green floating leaves are triangular with toothed edges and form rosettes around the end of the stem. Single small, white flowers with four 1/3-inch long petals sprout in the center of the rosette (New York Sea Grant, 2008).
T. natans is an annual aquatic plant with a submerged flexuous stem that anchors into the mud and extends upward to the surface of the water. T. natans features a rosette of floating, fan-shaped leaves, each leaf having a slightly inflated petiole (stem); the roots are fine, long and profuse. The small, 4-petalled flower is white and the fruit is a large nut with four sharp spines. (Methe et al 1993).
The plant’s cord-like stems are spongy and buoyant and can reach lengths of up to 16 feet (although typical lengths tend to be in the six to eight foot range). The stems are anchored to the bed of the water body by numerous branched roots (New York Sea Grant, 2008).
Size: stems to 16 feet
Native Range:
Europe, Asia and Africa
| ||
 Alaska |
Hawaii |
Caribbean |
Interactive maps: Continental US, Alaska, Hawaii, Caribbean
Nonindigenous Occurrences:
The water chestnut was first introduced to North America in the 1870s, where it is known to have been grown in a botanical garden at Harvard University in 1877. The plant had escaped cultivation and was found growing in the Charles River by 1879. The plant was introduced into Collins Lake near Scotia, NY (in the Hudson River-Mohawk River drainage basin) around 1884, possibly as an intentional introduction for waterfowl food or as a water garden escapee (New York Sea Grant, 2008).
Great Lakes Region-The first Great Lakes Basin introductions were sometime before the late-1950s in Keuka Lake (one of NY's Finger Lakes). Trapa can also be found in the Oswego River, a tributary of Lake Ontario; in Sodus Bay on Lake Ontario; in the Seneca River; and in Oneida Lake. These introductions may have been a result of transit through the Erie Canal, which connects to the Mohawk River.
Northeast: A major infestation of more than 300 acres exists throughout some 55 miles of Lake Champlain between New York and Vermont. Water chestnut can now be found in Connecticut, Maryland, Massachusetts, New York, Pennsylvania, Vermont and Virginia, and in the Canadian Province of Quebec in a tributary of the Richelieu River (most likely from a northward expansion of the Lake Champlain infestation). While established in the northeastern United States since the late 1800's, Trapa natans, continues to advance into new territory in New England and the Mid-Atlantic states. In the past 2 years, New Hampshire and Connecticut have experienced first occurrences of this robust floating aquatic plant that re-establishes each year from dangerously sharp-spined nuts.
Although new to the Nashua River, NH in 1998 and the Connecticut River, CT, in 1999, water chestnut is a repeat offender to tributaries of the Chesapeake Bay where plants were first experienced in the 1920s. Since 1997 plants have reappeared on the Bird and the Sassafras Rivers, tributaries of the northern Chesapeake Bay in Maryland.
Ecology: Trapa natans grows best in shallow, nutrient-rich lakes and rivers and is generally found in waters with a pH range of 6.7 to 8.2 and alkalinity of 12 to 128 mg/L of calcium carbonate. Trapa colonizes shallow (less than 16 feet deep) areas of freshwater lakes and ponds, and slow-moving streams and rivers, where it forms dense mats of floating vegetation.
Means of Introduction: Aquarium release. 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.
Status:
Established in Lake Ontario.
Impact of Introduction: Trapa natans outcompetes native plants for sunlight. It is a fierce competitor in shallow waters with soft, muddy bottoms. Uncontrolled, it creates nearly impenetrable mats across wide areas of water. In Vermont, USA, many previously fished bays of southern Lake Champlain are now inaccessible, and floating mats of T. natans can create a hazard for boaters. VDEC (2002) states that this noxious plant also severely limits the passage of light into the water, a critical element of a well-functioning aquatic ecosystem. It reduces oxygen levels, which may increase the potential for fish kills. T. natans outcompetes native vegetation and is of little value to wildfowl.
When
the plant occupies a site, most recreational activities such as swimming,
fishing from the shoreline, and the use of small boats are eliminated or
severely impeded. The primary economic costs related to T. natans are
associated with the costs of chemical and mechanical control efforts. It is also a human nuisance because mature T. natans nuts drift to shore where their sharp spines may hurt bare feet (Haber, 1999).
Remarks:
Unfortunately, an unrelated edible aquatic
plant, Eleocharis dulcis (Burm.f.) Trin. ex Henschel, a sedge in the
Cyperaceae, also is called water chestnut. The corm of E. dulcis is the
familiar water chestnut, or Chinese water chestnut, sold in cans and commonly
served in Chinese restaurants.
Nut-like fruit can be cooked, eaten out of hand, or used in other foods (Magness et al. 1971).
References
Fernald ML. 1950. Gray’s Manual of Botany. 8th ed. American Book Company, N.Y.
Gleason, H.A. 1957. The New Britton and Brown Illustrated Flora of the Northeastern U.S. and Adjacent Canada. New York Botanical Gardens, N.Y.
Global Invasive Species Database. 2008. http://www.issg.org/database
Methe BA, Soracco RJ, Madsen JD, Boylen CW. 1993. Seed production and growth of water chestnut as influenced by cutting. J. Aquat. Plant Manage. 31: 154-157.
Mills EL, Leach JH, Carlton JT, Secor CL. 1993. Exotic species in the Great Lakes: A history of biotic crises and anthropogenic introductions. Journal of Great Lakes Research 19: 1-54.
Vermont Invasive Exotic Plant Fact Sheet Series: Water Chestnut. Vermont Agency of Natural Resources and The Nature Conservancy, Vermont Chapter. June, 1998
Other Resources:
Ecology and Management of Invasive Plants Program. www.invasiveplants.net
NOAA Sea Grant Nonindigenous Species Site (SGNIS)
Author: Ling Cao
Contributing Agencies: 
NOAA - GLERL
Revision Date: 8/7/2009 Citation for this information:
Ling Cao. 2009. Trapa natans. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=263> Revision Date: 8/7/2009
| AccessibilityFOIAPrivacyPolicies and Notices | |
  |
|