Ludwigia grandiflora | Uruguayan Hampshire-purslane



Conservation status

Not Assessed

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).

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].

Native status


First reported in the wild



Invasive species - risk of High Impact

Irish status


Introduction pathways - 1

Escape from Confinement

Introduction pathways subclass - 1

Ornamental purpose

Invasive score


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:

Species Biology


"Herbaceous perennial and has two different growth forms: in one form glabrous or sparsely pubescent stems grow horizontally over the soil or water and produce roots at nodes and, often, white, spongy roots. These roots are feathery but stiff. Leaves are mostly glabrous, alternate, petiolate, but so congested at the tip to appear to be in rosettes. Leaf shape varies from suborbicular to obovate to spatulate with a round apex and base. Plants do not flower when only floating leaves are present. In the other growth form, plants elongate from the rosette stage (described above) and grow above the surface of the water. The stems are pubescent and erect, up to 1 m tall. The leaves are pubescent, variable in shape from lanceolate to elliptic and acute at both ends. Upper leaves may be subsessile or sessile, the lower leaves petiolate. Flowers are solitary from the upper leaf axils and on stalks 2 to 3 cm long. Sepals and petals are 5, sometimes 6, the petals bright yellow. The fruit is a pubescent capsule with many seeds." (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). 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. Initial records were from garden and ornamental 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

Management approach

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 grandiflora to Ireland.


Areas undergoing eradication should be fenced off and signed 'Uruguyan Hampshire-purslane eradication area. Please keep out.' Biosecurity is essential in preventing the spread of this invader (Renals, 2016).


Hand-pulling is an effective method for individual small areas of establishment (Q-bank, 2011).


For areas above the waterline and those in shallow water effective control can be achieved by excavating the top 30cm of topsoil (Q-bank, 2011).


Defra (2007) and 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. The first application should occur before June or July (Q-bank, 2011). 


Strategic planting of shrubs and trees may be useful to control individual stands but non-target species may also be affected.

Raising water levels can be very effective if the site allows (Q-bank, 2011).

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. 

Broad environment


Habitat description

Slow moving, freshwater including canals, lakes and ponds (Millane & Caffrey, 2014).

Species group


Native region

North America, South America

Similar species

Ludwigia peploides, Ludwigia hexapetala


World distribution(GBIF)

Irish distribution

Occasionally present- Rare/Localised. Detected at two sites in 2009, Inland Fisheries Ireland undertook action to remove the species from both sites and to monitor the sites.

Native distribution

Native from Argentina to the USA (Millane & Caffrey, 2014).

Temporal change

Date of first record category


Fifty year date category


Records submitted to Data Centre in 2022

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. 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. 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.

Q-bank. (2011). Ludwigia grandiflora (Michx.) Greuter & Burdet A guide to Identification, Risk Assessment and Management. Plant Protection Service, Wageningen, NL; Centre for Ecology and Hydrology, Wallingford, UK. Site accessed 29 August 2017.

Renals, T. (2016). Water Primrose Ludwigia grandiflora A Management Guide for Landowners. Version 1 (2016). Environment Agency. Site accessed 29 August 2017.

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.

CABI Datasheet

Ludwigia species Exclusion Strategy and Invasive Species Action Plan

Additional comments

Due to the taxonomic confusion surrounding and similar mechanisms of impact of Ludwigia grandiflora & Ludwigia hexapetala, Ludwigia hexapetala is not given its own entry.