Impatiens glandulifera | Indian Balsam | Lus na pléisce
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].
First reported in the wild
Invasive species - risk of High Impact
Introduction pathways - 1
Escape from Confinement
Introduction pathways subclass - 1
NAPRA Ireland risk assessed
Annual herb, erect stem up to 2m, flowers deep pink or purple to white, leaves opposite and in whorls of 3, 2.5-4cm (Stace, 1997).
Can cause soil erosion on river banks, as well as affecting downstream, instream communities by the addition of nutrient rich sediment (Greenwood & Kuhn. 2014). Presence of I. glandulifera may decrease plant species richness by 25% (Hulme & Bremner, 2006), as well as promoting the spread of other invasive species, even upon removal, by altering the soil fungal communities (specifically the arbuscular mycorrhizal fungi (AMF)) to the detriment of native species (Tanner & Gange, 2013). Stands of I. glandulifera support a lower diversity of Coleoptera and Heteroptera insect species than similar uninvaded plots (Tanner et al., 2014).
Mires, bogs & fens; Heath, scrubland & tundra; Woodland, forest and other wooded land; Regularly or recently cultivated agricultural, horticultural or domestic habitat
Seed production in I. glandulifera is dependent on plant density, with seed production decreasing with increased plant density but range from 500 - 2500 seeds per plant (Beerling & Perrins, 1993).
Pathway and vector description
Previously popular garden plant promoted by bee keepers (Millane & Caffrey, 2014), in some cases it escaped from cultivation, though it may have been deliberately spread as was the case in the UK (Rotherham, 2000).
Mechanism of impact
Found on riversides, roadsides, waste ground and former cultivated fields, prefers damp ground (Reynolds, 2002).
Established - Widespread. Locally abundant, naturalised though still spreading, can form dense stands (Reynolds, 2002).
Originally native to the Himalayan mountain region this species has been cultivated in China for centuries and those plants may represent the source of the introduction (Rotherham, 2000).
Date of first record category
Fifty year date category
Records submitted to Data Centre in 2017
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. Do not purchase this plant. Dispose of garden waste responsibly and never plant non-native species in the wild.
Delivering Alien Invasive Species In Europe (DAISIE) project list this as one of the 100 Worst Invaders in Europe.
Beerling, D.J. and Perrins, J.M. (1993) Impatiens glandulifera Royle (Impatiens roylei Walp.). Journal of Ecology, 81, 367-382.
Greenwood, P., & Kuhn, N. J. (2014). Does the invasive plant, Impatiens glandulifera, promote soil erosion along the riparian zone? An investigation on a small watercourse in northwest Switzerland. Journal of Soils and Sediments, 14(3), 637-650.
Hulme P.E & Bremner E.T., 2006. Assessing the impact of Impatiens glandulifera on riparian habitats: partitioning diversity components following species removal. Journal of Applied Ecology, 43, 43-50.
Millane, M. & Caffrey, J. (2014). Risk Assessment of Impatiens glandulifera Royle – Himalayan Balsam. Report prepared for Inland Fisheries Ireland and the National Biodiversity Data Centre.
Reynolds, S.C.P. (2002) A catalogue of alien plants in Ireland. National Botanic Gardens. Glasnevin, Dublin.
Rotherham. I.P. (2000). Exotic Invasive Species – should we be concerned? Himalayan balsam - the human touch. Proceedings of the Institute of Ecology and Environmental Management Conference, Birmingham, April, 2000.
Stace, C. (1997). New Flora of the British Isles 2nd Edition. Cambridge University Press, Cambridge.
Tanner, R. A., Varia, S., Eschen, R., Wood, S., Murphy, S. T., & Gange, A. C. (2013). Impacts of an invasive non-native annual weed, Impatiens glandulifera, on above-and below-ground invertebrate communities in the United Kingdom. PloS one, 8(6), e67271.
Tanner, R. A., & Gange, A. C. (2013). The impact of two non-native plant species on native flora performance: potential implications for habitat restoration. Plant Ecology, 214(3), 423-432.