Trapa natans 

Scope: Pan-Africa
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: 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.

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.
Countries occurrence:
Algeria; 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
Additional data:
Upper elevation limit (metres):150
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).
Current Population Trend:Stable
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.

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.

Classifications [top]

5. Wetlands (inland) -> 5.1. Wetlands (inland) - Permanent Rivers/Streams/Creeks (includes waterfalls)
suitability:Suitable  major importance:Yes
5. Wetlands (inland) -> 5.5. Wetlands (inland) - Permanent Freshwater Lakes (over 8ha)
suitability:Suitable  major importance:Yes
5. Wetlands (inland) -> 5.7. Wetlands (inland) - Permanent Freshwater Marshes/Pools (under 8ha)
suitability:Suitable  major importance:Yes
15. Artificial/Aquatic & Marine -> 15.2. Artificial/Aquatic - Ponds (below 8ha)
15. Artificial/Aquatic & Marine -> 15.9. Artificial/Aquatic - Canals and Drainage Channels, Ditches
suitability:Suitable  major importance:Yes
1. Land/water protection -> 1.1. Site/area protection
2. Land/water management -> 2.1. Site/area management
2. Land/water management -> 2.3. Habitat & natural process restoration
5. Law & policy -> 5.1. Legislation -> 5.1.1. International level
5. Law & policy -> 5.1. Legislation -> 5.1.2. National level
5. Law & policy -> 5.4. Compliance and enforcement -> 5.4.2. National level

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
In-Place Species Management
In-Place Education
1. Residential & commercial development -> 1.1. Housing & urban areas
♦ timing:Ongoing    
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

1. Residential & commercial development -> 1.3. Tourism & recreation areas
♦ timing:Ongoing    
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

5. Biological resource use -> 5.4. Fishing & harvesting aquatic resources -> 5.4.6. Motivation Unknown/Unrecorded
♦ timing:Future    

7. Natural system modifications -> 7.2. Dams & water management/use -> 7.2.4. Abstraction of surface water (unknown use)
♦ timing:Ongoing    

1. Research -> 1.2. Population size, distribution & trends
1. Research -> 1.3. Life history & ecology
1. Research -> 1.5. Threats
1. Research -> 1.6. Actions
3. Monitoring -> 3.1. Population trends

♦  Food - human
 Local : ✓   National : ✓ 

♦  Pets/display animals, horticulture
 Local : ✓ 

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 2010: e.T164153A5752471. . Downloaded on 21 August 2018.
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