Trapa natans

[Regional assessment]

Taxonomy [top]

Kingdom Phylum Class Order Family

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

Assessment Information [top]

Red List Category & Criteria: Least Concern (Regional assessment) ver 3.1
Year Published: 2010
Date Assessed: 2009-05-05
Assessor(s): Diop, F.N.
Reviewer(s): Ghogue, J.-P., Ali, M.M. & Smith, K.G
This plant is widespread in Africa and where it occurs it is often abundant. The species has invasive tendencies, so this could become a problem in the future. Therefore it is listed as Least Concern.
2013 Least Concern
2010 Least Concern (IUCN 2011.1)

Geographic Range [top]

Range Description:Trapa natans is an Eurasiatic (palaeo-temperate) species, introduced in Africa and North America, where it is locally invasive. It has been argued that the species in not native to Africa, however, as it has been collected from supposedly wild places, it is treated as native.

Its North Africa it is found in Algeria (very rare in El Kala, Annaba) and Tunisia (very rare, Ichkeul marsh).

In Eastern Africa, this species is uncommon, only recorded in Lake Victoria Area in Kisii (K5). Tanzania T1,4. Lake Province Ukerewe, Kigoma district Lake Tanganyika. Also present in Uganda and Malawi. In South Africa, it is only present in KwalaZulu-Natal

In North Eastern Africa it is only found in Sudan (South reaches of the White Nile) and it has a scattered range in western Africa.
Algeria; Angola (Angola); Botswana; Burkina Faso; France (France (mainland)); Ghana; Greece (Greece (mainland)); Guinea; Guinea-Bissau; Italy (Italy (mainland)); Kenya; Malawi; Mozambique; Namibia; Niger; Nigeria; South Africa (KwaZulu-Natal); South Sudan; Sudan; Tanzania, United Republic of; Tunisia; Turkey (Turkey-in-Asia, Turkey-in-Europe); Uganda; Zambia; Zimbabwe
Range Map:Click here to open the map viewer and explore range.

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), France and Italy (unknown).
Population Trend: Stable

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.
Systems: Freshwater

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.

Conservation Actions [top]

Conservation Actions: In France, the species is protected at regional level (Alsace, Basse-Normandie, Limousin) and at departemental 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 ones.
- Evaluation of the size of populations.
- Study of the dynamics of populations.

Bibliography [top]

Pan-Africa freshwater assessment references. Currently, full citations for references used in the Pan-Africa biodiversity assessments are unavailable on the Red List web site. These will be added to the site in 2011. We apologize for any inconvenience this causes.

IUCN. 2010. IUCN Red List of Threatened Species (ver. 2010.3). Available at: (Accessed: 2 September 2010).

Citation: Diop, F.N. 2010. Trapa natans. In: The IUCN Red List of Threatened Species. Version 2014.3. <>. Downloaded on 27 March 2015.
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