European water-chestnut
Trapa natans L.
Water chestnut Family (Trapaceae)
David Frush
PBIO 209 Plant Ecology
Winter 2008, Ohio University
Prof Kim J. Brown
I picked this plant, European water-chestnut, because I knew very little about. I used this project to further my knowledge on this plant.
European water-chestnut: Common
Description - European water chestnut is an aquatic plant, which is usually rooted in the mud; it bears a rosette of floating leaves at the tip of the submersed stem. Although it grows best in shallow, nutrient-rich lakes and rivers, it can also grow on wet, mucky substrates.
Stems - Stems are elongate, flexuous and typically about a meter long but may reach as much as 5 meters in length.
Leaves - The conspicuously toothed leaf blades are ½–1 inch long and rhombic in utline with (four sides); the spongy, inflated leaf stalks are up to 3 inches long and provide the buoyancy to keep the terminal leafy portion of the plant floating at the water surface. Green, feather-like, submersed leaves (considered by some to be modified roots) with very fine segments are present on the underwater portion of the stem.
Roots - Numerous finely branched roots develop along the lower stem and assist in anchoring the plant to the substrate.
Flowers - The inconspicuous flowers with their four white petals, each about 1/3 inch long are borne singly on erect stalks located in the central area of the leafy rosette.
Fruit - The fruit is a black, four-horned, nut-like structure, about an inch wide, that develops under water.
Pictures of the European water-chestnut
http://pbio209.pbwiki.com/f/image001.gif
Photos: Leslie J. Mehrhoff, University of Connecticut, IPANE,
http://invasives.eeb.uconn.edu/ipane/
Photo: Leslie J. Mehrhoff, University of Connecticut, IPANE,
http://invasives.eeb.uconn.edu/ipane/
Photo: plants.usda.gov/ maps/large/TR/TRNA.png
REPRODUCTION AND METHODS OF DISPERSAL
In our climate European water-chestnut is an annual. (According to Gurevitch, Scheiner, and Fox. Annual means that plants that vegetative lifestyle is completed in less then a year.) Both vegetative reproduction and seed production take place at this time. (The Ecology of Plants)
Flowers are produced singly on stalks arising from the leaf axils. Each flower is bisexual, bearing a two-chambered ovary, four stamens and four white petals. Once the ovules of the insect-pollinated flowers are fertilized, the flower stalks curve downward with the result that the fruits develop under water. The ovary and surrounding sepals mature into a nut-like, barbed spiny fruit. Flowering begins in the northeastern United States in July and fruits ripen in about a month. The plants continue to flower until killed by frost. One acre of water chestnut can produce enough seeds to cover 100 acres the following year. Each seed can give rise to 10–15 rosettes, and each rosette may produce as many as 20 seeds. Seeds have been known to remain viable for up to 12 years.
The fruits may be dispersed when individual plants are uprooted and float downstream. Fruits fall to the bottom of the water body in the autumn and the seeds over winter just as in terrestrial annual species. Seeds germinate in the spring, with the young root (radicle) perforating the top of the fruit. The young plants develop narrow, opposite leaves initially. As the plant matures, the typical floating, leafy rosettes form at the end of the expanding stem. As soon as the initial shoot develops floating leaves, additional leafy offshoots are produced at a rapid rate. Some of these may become detached and develop into separate plants. It has been suggested that in warmer climates some plants may persist as short-lived perennials (European).
DISTRIBUTION AND HABITAT
European water chestnut is native to tropical and warm temperate regions of Eurasia. The plants have become widely distributed throughout Europe. The plants apparently were introduced into Switzerland during the period of the lake dwellings (around 3000 BC).
In the Americas, European water-chestnut is an invasive species known for its aggressive growth habits. Wild populations have since become established in many locations in the northeastern United States. To help control the spread of European water-chestnut, the sale of all species of Trapa is banned in most of the southern United States.
Plants grow in quiet streams, ponds, freshwater regions of estuaries, and on exposed mud flats. The widespread occurrence of water-chestnut in aquatic habitats of the northeastern United States is in marked contrast with its present status as a rare species in a number of European countries
EFFECTS OF INVASION
The plants have become an aquatic nuisance species in North America because of their ability to reproduce rapidly and form extensive floating mats. Due to its dense growth, the species impedes navigation and its low food value for wildlife potentially can have a substantial impact on the use of an area by waterfowl and other native species. The dense surface mats likely also inhibit the growth of other aquatic plant species. Decomposition of the abundant detritus produced in the fall of each year as the plants senesce, could contribute to lower oxygen levels in shallow waters and thus impact other aquatic organisms. With four, hard, half-inch spines that are sharp enough to penetrate shoe leather and large enough to keep people off beaches, the seeds are a major hazard to water-based recreation (Trapa natans).
Part II
The European water chestnut is a small green plant that grows in lakes, ponds and other bodies of water in North America and southern Canada. The biome that the European
water chestnut grows in is the Temperate Broadleaf and Mixed Forest. The scientific name for the European water chestnut is Trapa natans L. Presently the species is found in Maryland,
Massachusetts, New York, Pennsylvania and Vermont. In 1998, it was reported for the first time in Canada, in southwestern Quebec. While not yet widespread in Pennsylvania, it is
known from scattered sites in the eastern part of the state. It is an invasive species that is wreaking havoc on many ecosystems.
The European water chestnut is native to tropical and warm temperate regions of Eurasia also Europe, Asia and Africa. It has become naturalized in Australia and in northeastern North
America. The Water- chestnut Family contains only a single genus. Because the fruits have been used as a source of food and for their medicinal and reputed magical properties, the
plants became widely distributed throughout Europe. The plants apparently were introduced into Switzerland during the period of the lake dwellings (around 3000 BC). 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. Water chestnut favors
nutrient-rich waters with a pH range of 6.7 to 8.2 and an alkalinity of 12 to 128 mg/l of calcium carbonate (water chestnut).
There is always is and going to be an abundance of lakes, ponds, and rivers so, the European water chestnut really does not have to stress about losing these bodies of water or the
habitats that they grow in. In other words the plant does not have any potential threats to the habitat where the plant lives within. Also the European Water chestnut is an invasive
species so it is the plant that is the threat to all the other plant and animal life in the areas that it surrounds and inhabits.
The Water chestnut has become a significant nuisance throughout much of its range, particularly in the Hudson, Connecticut and Potomac Rivers, and in Lake Champlain. In its
native habitat, the plant is kept in check by native insect parasites. These insects are not present in North America and the plant, once released into the wild, is free to reproduce rapidly.
The plant can form nearly impenetrable floating mats of vegetation. These mats create a hazard for boaters and other water occupants. The density of the mats can severely limit light
penetration into the water and reduce or eliminate the growth of native aquatic plants beneath the canopy. The water chestnut plants which die back each year can also result in reduced
levels of dissolved oxygen in the water, impact other aquatic organisms, and potentially lead to killing the surrounding fish. The water chestnuts rapid and abundant growth can also
out-compete native aquatic vegetation (water chestnut).
Water chestnut has little nutritional or habitat value to fish or waterfowl and can have a significant impact on the use of an infested area by native species. The water chestnuts
have sharp, spiny nuts can result in puncture injuries to people walking along the shore of infested areas. Because of its invasiveness and the severity of its impacts, the species has been
listed under the federal regulations that prohibit the interstate sale and transportation of noxious plants.
The water chestnut species is not the same as the “water chestnut” which can be purchased in cans at the supermarket and which is used in Asian cooking. The fruits of Trapa natans,
however, are used as a source of food in Asia and have been utilized for their medicinal (and claimed) magical properties (Trapa natans L. water chestnut).
REFERENCES
Gurevitch J, Scheiner S, Fox G. 2006. The Ecology of Plants. Sunderland, MA: Sinauer Associates, Inc. 574 p.
European water-chestnut. Internet. : University of Pennsylvania . cited 2008 Feb 18. Available from http://www.paflora.org/Trapa%20natans.pdf
Trapa natans L. water chestnut. Internet. : US Department of Agriculture. cited 2008 Feb 18. Available from http://plants.usda.gov/java/profile?symbol=TRNA
1 Photos: Leslie J. Mehrhoff, University of Connecticut, IPANE,
http://invasives.eeb.uconn.edu/ipane/
2 Photo: Leslie J. Mehrhoff, University of Connecticut, IPANE,
http://invasives.eeb.uconn.edu/ipane/
3 Photo: plants.usda.gov/ maps/large/TR/TRNA.png
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