Cabomba caroliniana | Carolina Water-shield

Pre 2017

2017 - 2020


Legal status

Third Schedule listed species under Regulations 49 & 50 in the European Communities (Birds and Natural Habitats) Regulations 2011. (Note: Regulation 50 not yet enacted).

Regulated invasive  species of Union concern under the European Regulation on the prevention and management of the introduction and spread of invasive alien species [1143/2014].


Not assessed

Irish status


Introduction pathways - 1

Release in Nature

Introduction pathways subclass - 1

Botanical garden/zoo/aquaria

NAPRA Ireland risk assessed


Species Biology


Perennial, herbaceous dark green aquatic plant. Normally fully submerged and rooted in the substrate. However, can survive unrooted for 6-8 weeks (GISD, 2015). Found in stagnant and slow flowing freshwater including small rivers, ponds, lakes, streams, ditches, canals and reservoirs. Submerged leaves are fan-shaped, opposite and deeply divided, giving a feathery appearance. Stems up to 10m long (Australian Department of the Environment and Heritage, 2003; GISD, 2015). Flowers small white to pale yellow, sometimes with a tinge of pink or purple, appear above the water during the summer so the plant may be more in evidence at this time of the year. 


Reduces biodiversity. Shades out native species by rapid, thick growth (EPPO, 2007). Also competes for space and nutrients (Australian Department of Environment and Energy, undated). Large stands block waterways.

Negative social impacts (EPPO Bulletin, 2014) and aesthetic impacts (NNSS, 2012). Decline in tourism around affected waterways due to a decrease in recreational use as the long stems interfere with boats, other equipment, fishing lines and may pose a danger to swimmers (Schooler et al.,2005).

Reduced oxygen levels arising from the decay of large swaths of the plant may result in fish kills (Commonwealth of Massachusetts, 2002).


Inland surface waters.


The main method of reproduction and spread outside its native range is vegetative from stem fragments and via rhizomes (EPPO, 2007). A single pair of leaf nodes is all that is required to produce a new plant (Schooler et al., 2005). During the Autumn the leaves dies back and the stems become brittle allowing fragments to break off more readily (Mackey, 1996) facilitating its spread. These stem fragments can survive under ice covered water and regrow the following spring (Mackey, 1996).  

Pathway and vector description

The attractive foliage and flowers of this plant make it a popular choice as an aquarium plant and it is readily purchased online. It is introduced into the wild by improper disposal of aquarium water and contents (EPPO, 2007). From there it is easily spread between waterways on boats, equipment and possibly by waterfowl (Schooler et al., 2005).

Mechanism of impact


Management approach

There is currently an EU wide ban on the sale, growing and keeping of this plant (European Commission, 2017).

Preventing dumping of aquarium into natural habitats is essential in keeping this species out of Ireland. Flyers, posters, online information and identification aids should help to promote responsible disposal of aquarium contents (EPPO, 2014). Providing relevant organisations and individuals with information about native alternatives to Cabomba caroliniana should help to lessen the demand for the plant (Australian Department of Environment and Heritage, 2003).

Environmental Control

Once Cabomba caroliniana is established control can be achieved by planting trees and large plants beside problem areas to shade out the plant (NNSS, 2012). Experimental work in Lough Corrib uses benthic barriers (jute mats) to control another submerged species; Lagarosiphon major (Caffrey, 2010) and this may be effective too for Cabomba caroliniana. Where feasible water level drawdown can work provided the water can be excluded completely for an adequate period (Australian Department of the Environment and Heritage, 2003).

Physical/Mechanical Control

Handpulling and mechanical options can used but may in fact contribute to spread due to the fragmentation of the stems (NNSS, 2012). Hussner et al. (2017) mention Hydro-Venturi (water jets) as an effective means of control with less fragmentation than other mechanical means.

Broad environment


Habitat description

Slow moving or still freshwater lakes, rivers, ponds, canals, streams, ditches and reservoirs. It is usually found in water less than 3m deep but can be found up to 10m deep (Australian Department of the Environment and Heritage, 2003; GISD, 2015). 

Species group


Native region

South America


World distribution(GBIF)

Native to South America. It is regarded as invasive in Japan, Australia, USA, and Canada. It has been introduced to China, India, Malaysia, New Guinea, New Caledonia (NNSS, 2012), UK, Netherlands, Hungary, France, Belgium, Austria, Denmark, Poland and Sweden (European Commission, 2017). It is not regarded as invasive in Europe but has become problematic at a site in both France and the Netherlands (NNSS, 2012).

Native distribution

Southern Brazil, Paraguay, Uruguay, Northeastern Argentina, Central America and the West Indies. It may also be native to Southern parts of North America (NNSS, 2012).

Temporal change

Records submitted to Data Centre in 2024

The following map is interactive. If you would prefer to view it full screen then click here.

How can you help

Report any sightings to the National Biodiversity Data Centre. Dispose of aquarium plants responsibly. Do not purchase or plant in your garden.



Australian Department of Environment and Energy. (undated). Cabomba caroliniana. Canberra. Department of Environment and Energy. Site accessed 30 August 2017.

Australian Department of the Environment and Heritage. (2003). Cabomba (Cabomba caroliniana): weeds of national significance. Weed management guide. [Adelaide]. The CRC for weed management. Site accessed 27 July 2017.

Caffrey, JM et al. (2010). A novel approach to aquatic weed control and habitat restoration using biodegradable jute matting. Aquatic Invasions, 5(2), pp. 123-129. Site accessed 4 August 2017.

Commonwealth of Massachusetts~Department of Conservation and Recreation~Office of Water Resources~Lakes and Ponds Program. (2002). Fanwort: an invasive aquatic plant Cabomba caroliniana. Factsheet. [Boston]. Office of Water Resources. Site accessed 31 July 2017.

EPPO. (2007). Data sheets on onvasive alien plants. Cabomba caroliniana. European and Mediterranean Plant Protection Organisation. [Paris]. Site accessed 20 July 2017.

EPPO. (2014). PM9/19 (1) Invasive alien aquatic plants. EPPO Bulletin, 44, pp. 457-471. Site accessed 2 August 2017.

European Commission. (2017). Invasive Alien Species of Union Concern. European Union, Luxembourg.

GB Non-native Species Secretariat (NNSS). (2012). Carolina Fanwort (Cabomba caroliniana). Risk Assessment (risk assessment prepared for Great Britain). Site accessed 2 August 2017.

Global Invasive Species Database. (2015). Species profile Cabomba caroliniana. Site accessed 26 July 2017.

Hussner, A et al. (2017). Management and controlmethods of invasive alien freshwater aquatic plants: a review. Aquatic Botany, 136 (January), pp. 112-137. Site accessed 4 August 2017.

Mackey, AP (1996). Cabomba (Cabomba spp.) in Queensland. Pest status review series- Land Protection Branch. Queensland. Department of Natural Resources and Mines. Site accessed 2 August 2017.

Schooler, SS, Williams, DG, Stokes, K, Julien, M (2005). Invasive plants: impacts and

management in rivers and catchments. Riversymposium. Site accessed 28 July 2017.

CABI Datasheet (

Global Invasive Species Database (

Additional comments

The risk assessment carried out for Great Britain (NNSS, 2012) concludes that summers in the United Kingdom may be too short for Cabomba caroliniana to become invasive. However, climate change may favour plant establishment in both the United Kingdom and Ireland.