Trapa natans 

Scope: Mediterranean
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Myrtales Trapaceae

Scientific Name: Trapa natans L.
Regional Assessments:
Common Name(s):
English Water Caltrop, Water Chestnut
French Châtaigne d'Eau, Mâcre, Mâcre nageante
Trapa astrachanica (Flerow) N.A.Winter
Trapa carinthiaca (Beck) V.N.Vassil.
Trapa colchica Albov
Trapa conocarpa (F.Aresch.) Flerow
Trapa cruciata (Glück) V.N.Vassil.
Trapa europaea Flerow
Trapa hungarica Opiz
Trapa maeotica Woronow
Trapa muzzanensis (Jäggi) Szafer
Trapa rossica V.N.Vassil.
Trapa septentrionalis V.N.Vassil.
Trapa spryginii V.N.Vassil.

Assessment Information [top]

Red List Category & Criteria: Data Deficient (Regional assessment) ver 3.1
Year Published: 2010
Date Assessed: 2008-09-01
Assessor(s): Daoud-Bouattour, A., Gammar-Ghrabi, Z., Limam-Ben Saad, S. & Muller, S.D.
Reviewer(s): Bilz, M. & Lansdown, R.
Contributor(s): García Murillo, P.G.
Trapa natans is more widespread in northern Europe and rare along the Mediterranean coast. The populations in North Africa and Turkey are declining, but there is no precise information on area of occupancy or extent of occurrence available. The situation of the species in the Balkans needs to be clarified and more information is needed in order to carry out an assessment. It is therefore classed as Data Deficient.

Geographic Range [top]

Range Description:Trapa natans is an Eurasiatic (palaeo-temperate) species, introduced in Africa and North America, where it is locally invasive.

Its Mediterranean distribution extends to Algeria (very rare, El Kala, Annaba), Tunisia (very rare, Ichkeul marsh), northern Greece (rare), Turkey, Balkans (Albania, Bulgaria, Croatia, Montenegro, Serbia, Slovenia), and northern Italy. It is extinct in Spain.

It occurs in France and is widespread, but absent from the Mediterranean coast and Corsica (Tela Botanica 2009).

This species is also found in other parts of Europe and in Asia.
Countries occurrence:
Albania; Algeria; Bulgaria; Croatia; Greece (Greece (mainland)); Italy (Italy (mainland)); Montenegro; Serbia; Slovenia; Tunisia; Turkey (Turkey-in-Asia, Turkey-in-Europe)
Regionally extinct:
Spain (Baleares, Spain (mainland))
Additional data:
Upper elevation limit (metres):150
Range Map:164153-3

Population [top]

Population:Trapa natans is very rare in the Mediterranean basin and in North Africa: Algeria (two sub-populations), Tunisia (one sub-population), Greece (two sub-populations), Turkey (common in the European part and present at three lakes in the southeastern part at the Marmara sea), it is common and even slightly invasive in the Balkans (Croatia, Montenegro, Slovenia and Albania). It is not clear whether the invasive species in the Balkans are T. natans or other species belonging to the genus.

In Spain, Trapa natans had been recorded from Girona (Sils) and Mallorca (Albufera de Alcudia) many decades ago, but now it is Extinct in the Iberian Peninsula (Castroviejo et al. 1997).
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Trapa natans is an annual (up to 3 m height) floating-leaved plant, growing in stagnant waters, lakes, channels with weak currents, ponds and marshes.

Use and Trade [top]

Use and Trade: Trapa natans produces a floury fruit, sweet and edible. It is taken from the wild and planted in private gardens.

Threats [top]

Major Threat(s): The subpopulations of Algeria and Tunisia are threatened by the changing conditions of the lakes where it develops. The same is the case for Turkey where the water extraction for agricultural purposes is a threat to the plant. In some parts of Turkey, the plant is taken from the wild and replanted in water gardens - this is not a threat now but could become one in the future.
In Algeria, Lake Oubeira has been opened for fishing and that could impact on the existing population in the future.
Overall, changes of habitat to agriculture and water eutrophication are the main threats to the species habitat.

Conservation Actions [top]

Conservation Actions: In France, the species is protected at regional level (Alsace, Basse-Normandie, Limousin) and at departmental level (Ardennes). In Tunisia it occurs in the National Park of Ichkeul. In Turkey, Trapa natans is classified as Vulnerable on the national Red List.

The following conservation measures are recommended:
- Legal protection
- Application of legal measures of conservation.
- Monitoring of the sub-populations and search for new and historic sites in North Africa and the Balkans.
- Evaluation of the size of populations.
- Study of the dynamics of populations.

Citation: Daoud-Bouattour, A., Gammar-Ghrabi, Z., Limam-Ben Saad, S. & Muller, S.D. 2010. Trapa natans. The IUCN Red List of Threatened Species 2010: e.T164153A5752200. . Downloaded on 26 September 2018.
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