Third Schedule listed species under Regulations 49 & 50 in the European Communities (Birds and Natural Habitats) Regulations 2011. (Note: Regulation 50 not yet enacted).
Listed as a schedule 9 species under Articles 15 & 15A of the Wildlife Order (Northern Ireland) 1985 (Article 15A 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].
Invasive species - risk of High Impact
Introduction pathways - 1
Escape from Confinement
Introduction pathways subclass - 1
NAPRA Ireland risk assessed
Yes. This species underwent a Non-native species APplication based Risk Analysis in 2014.
Overall risk of this species to Ireland is categorised as: MAJOR with a VERY HIGH level of confidence.
Overall conclusion summary: The three Ludwigia spp. assessed appear to pose a major risk to native biodiversity, native ecosystems and conservation goals as well as having the potential to cause negative socio-economic impacts in slow-flowing or still waters due to their capacity to spread rapidly and establish dense infestations. The Irish climate appears to be very suitable for the establishment of L. peploides and L. hexapetala and it has already been demonstrated that it is suitable for the establishment of L. grandiflora.
View the full risk assessment: http://nonnativespecies.ie/wp-content/uploads/2014/03/Ludwigia-spp-Water-Primrose1.pdf
"Creeping water primrose is a creeping or floating aquatic perennial herb that sometimes forms mats. Stems and leaves are usually glabrous or sometimes sparsely pubescent. The leaves are alternate, simple, and net-veined. Leaves of the floating stems are oblanceolate to spatulate, or sometimes orbicular in shape. Stems bearing flowers are usually weakly upright with lanceolate to narrowly elliptic leaves. Leaf petioles are 1 to 5 cm long. Flowers are axillary, perfect, and solitary on stalks 1 to 5 cm long. The five petals of the flower are yellow. The fruit is a cylindrical capsule with numerous seeds. Seeds are ellipsoid, yellowish, and less than 1 mm long." (USACE-ERDC 2009).
A strong negative relationship between Ludwigia grandiflora cover and invertebrate abundance & native plant abundance were measured in pond experiments in Belgium (Stiers et al., 2011) and L. peploides would be expected to have similar impacts. Can form dense mats covering over waterbodies with measured dry biomass(DM) of Ludwigia spp. varying from 200 g DM per metre squared in shallow lakes to 4,500 g DM per m squared in a meander of a eutrophicated river (Lambert et al., 2010). Has been shown to engage in allelopathic activity (releasing chemicals to affect other organisms) that influences the water quality throughout the year, giving it a competitive advantage over Lactuca sativa (Dandelot et al., 2008).
Inland surface waters
Can spread vegetatively and regenerates freely (Millane & Caffrey, 2014).
Pathway and vector description
Sold as an ornamental plant for outdoor ponds. From there it has the potential to spread to natural waterways, by natural means during flood events or through 'aquarium dumping' of material in the wild. (Millane & Caffrey, 2014)
Mechanism of impact
Competition, Poisoning/Toxicity, Bio-fouling
There is currently an EU wide ban on the sale, growing and keeping of this plant (European Commission, 2017).
Well established stands may be impossible to eradicate (Millane & Caffrey, 2014). The Department for the Environment, Food & Rural Affairs in the UK (Defra) (2007) advises eradication is only possible within the first year of establishment. Kelly and Maguire (2009) recommend a combination of chemical, environmental and mechanical methods.
Publicity campaigns, education of gardeners and water users, and promotion of responsible disposal of aquarium plants should help to prevent further introductions of Ludwigia peploides to Ireland.
Biosecurity is essential in preventing the spread of this species. New plants can grow from very small pieces of plant material. Areas undergoing eradication should be clearly signed.
Smaller infestations can be cleared by hand-pulling (Kelly and Maguire, 2009). Care must be taken to remove the entire plant.
Cutting or chaining (raking) can be used for heavy infestations (Kelly and Maguire, 2009) but containment nets must be in place to trap any loose fragments.
Kelly & Maguire (2009) recommend the use of an adjuvant as Ludwigia spp. may be tolerant of low concentrations of glyphosate. Several applications each season are necessary to achieve control. Mechanical means can be used to remove as much material as possible before flowering and the regrowth can then be sprayed (Kelly and Maguire, 2009).
Strategic planting of shrubs and trees may be useful to control individual stands but non-target species may also be affected (Defra, 2007).
Benthic barriers (jute matting) have been used to successfully control Lagarosiphon major in Lough Corrib (Caffrey, 2010). This method may also have an application in the control of Ludwigia spp.
Slow moving, freshwater including canals, lakes and ponds (Millane & Caffrey, 2014).
North America, South America
Ludwigia grandiflora, Ludwigia hexapetala
Native from Argentina to the USA (Millane & Caffrey, 2014).
Records submitted to Data Centre in 2023
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.
Practice good biosecurity protocols when moving boats and fishing equipment by thoroughly disinfecting all gear.
Do not dump aquatic plants in waterways or stock non-indigenous aquatic plants in outdoor ponds or lakes.
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. http://www.aquaticinvasions.net/2010/AI_2010_5_2_Caffrey_etal.pdf Site accessed 4 August 2017.
Dandelot, S., Robles, C., Pech, N., Cazaubon, A., & Verlaque, R. (2008). Allelopathic potential of two invasive alien Ludwigia spp. Aquatic Botany, 88(4), 311-316.
Department of the Environment, Food and Rural Affairs (Defra). (2007). Eradication strategies for invasive non-native Ludwigia spp. - PH0422. Research project final report. SID5. http://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location=None&Completed=1&ProjectID=14763 Site accessed 29 August 2017.
European Commission. (2017). Invasive Alien Species of Union Concern. European Union, Luxembourg.
Kelly, J., and Maguire, C.M. (2009). Water Primrose (Ludwigia species) Exclusion Strategy and Invasive Species Action Plan. Prepared for NIEA and NPWS as part of Invasive Species Ireland.
Lambert, E., Dutartre, A., Coudreuse, J., & Haury, J. (2010). Relationships between the biomass production of invasive Ludwigia species and physical properties of habitats in France. Hydrobiologia, 656(1), 173-186.
Millane, M & Caffrey, J. (2014) Risk Assessment of Ludwigia spp. (Water Primroses). Report prepared for Inland Fisheries Ireland and the National Biodiversity Data Centre.
Stiers, I., Crohain, N., Josens, G., & Triest, L. (2011). Impact of three aquatic invasive species on native plants and macroinvertebrates in temperate ponds. Biological Invasions, 13(12), 2715-2726.
USACE-ERDC (2009). Aquatic Plant Information System (APIS). Aquatic Plant Information System (APIS). Vicksburg, Mississippi, USA: United States Army Corps of Engineers - Engineer Research and Development Center.