Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Impatiens glandulifera
(Himalayan balsam)



Impatiens glandulifera (Himalayan balsam)


  • Last modified
  • 27 September 2018
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Preferred Scientific Name
  • Impatiens glandulifera
  • Preferred Common Name
  • Himalayan balsam
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae
  • Summary of Invasiveness
  • I. glandulifera is a highly invasive annual species which has spread rapidly in many parts of Europe and North America after its introduction as an ornamental. The spread is likely to continue to more northerly...

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Monoculture of Impatiens glandulifera on the River Taw, North Devon, UK
TitleInvasive habit
CaptionMonoculture of Impatiens glandulifera on the River Taw, North Devon, UK
Monoculture of Impatiens glandulifera on the River Taw, North Devon, UK
Invasive habitMonoculture of Impatiens glandulifera on the River Taw, North Devon, UKCABI
Impatiens glandulifera in its native range (Pakistan).  In the native range the plant grows in clusters of 30-60 individuals no more than 1.5m tall.
TitleNatural habit in Pakistan
CaptionImpatiens glandulifera in its native range (Pakistan). In the native range the plant grows in clusters of 30-60 individuals no more than 1.5m tall.
Impatiens glandulifera in its native range (Pakistan).  In the native range the plant grows in clusters of 30-60 individuals no more than 1.5m tall.
Natural habit in PakistanImpatiens glandulifera in its native range (Pakistan). In the native range the plant grows in clusters of 30-60 individuals no more than 1.5m tall.CABI
Impatiens glandulifera in flower showing foliage and ripening seed capsules.
TitleFlowers and foliage
CaptionImpatiens glandulifera in flower showing foliage and ripening seed capsules.
Impatiens glandulifera in flower showing foliage and ripening seed capsules.
Flowers and foliageImpatiens glandulifera in flower showing foliage and ripening seed capsules.CABI
Close-up of Impatiens glandulifera flower.
CaptionClose-up of Impatiens glandulifera flower.
Close-up of Impatiens glandulifera flower.
FlowerClose-up of Impatiens glandulifera flower.CABI


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Preferred Scientific Name

  • Impatiens glandulifera Royle

Preferred Common Name

  • Himalayan balsam

Other Scientific Names

  • Balsamina glandulifera (Royle) Ser.
  • Balsamina macrochila (Lindl.) Ser.
  • Balsamina roylei (Walp.) Ser.
  • Impatiens glanduligera Lindley
  • Impatiens macrochila Lindl.
  • Impatiens roylei Walp.

International Common Names

  • English: custodian helmet; Indian balsam; ornamental jewelweed; policeman's helmet; purple jewelweed; touch-me-not; Washington orchid
  • Spanish: impaciencia
  • French: balsamie de l'Himmalaya; balsamine d'Inde; balsamine géante

Local Common Names

  • Denmark: kæmpe-balsamin; kjempespringfrø
  • Estonia: verev lemmalts
  • Finland: jättipalsami
  • Germany: Drüsiges Springkraut; Indisches Springkraut
  • Iceland: risalísa
  • Latvia: puku sprigane
  • Lithuania: bitine sprige
  • Netherlands: balsemien, reuzen-
  • Norway: kæmpe balsamin
  • Poland: niecierpek gruczolowaty; niecierpek himalajski
  • Sweden: jättebalsamin
  • USA: ornamental jewelweed

EPPO code

  • IPAGL (Impatiens glandulifera)

Summary of Invasiveness

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I. glandulifera is a highly invasive annual species which has spread rapidly in many parts of Europe and North America after its introduction as an ornamental. The spread is likely to continue to more northerly or high montane areas as a result of global climatic change. Due to its ability to form dense stands and its conspicuous appearance it has been blamed for negative biodiversity effects. Even though these effects are less severe than often thought, further spread is undesirable and should not be facilitated by further use, in particular in natural areas. Control is advisable in certain situations, e.g. nature reserves and conservation sensitive areas, but eradication from larger parts of its invasive range is not feasible due to the need to control the plant on a catchment scale, which is often impossible due to the sheer scale of occurrence and division of land ownership.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Dicotyledonae
  •                     Order: Balsaminales
  •                         Family: Balsaminaceae
  •                             Genus: Impatiens
  •                                 Species: Impatiens glandulifera

Notes on Taxonomy and Nomenclature

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Before the recent advances in molecular phylogenetics, Impatiens (Balsaminaceae) was treated as a distinctly separate order, Balsaminales (Dahlgren, 1989), and more traditionally as a member of the order Geraniales under Rosidae (Cronquist, 1988; Thorne, 2000). Anderberg et al. (2002) and Geuten et al. (2004) disputed such classifications which were based mainly on morphological characteristics. As a result of their molecular phylogenetic studies, Balsaminaceae was reclassified as a family in the Ericales (an order of 26 families), sitting as a sister group to all other Ericales in the Balsaminoid Ericales. The Balsaminoid Ericales consist of the families Balsaminaceae, Marcgraviaceae, Pellicieraceae and Tetrameristaceae. Together this group comprises of approximately 1130 species. Three ‘forms’ of the species have been noted, forma albida (Hegi) B. Boivin, forma pallidaflora Weath., and forma glandulifera Vahl (Missouri Botanical Garden, 2008).

Attention should be paid to the taxonomic authority, as the true species is I. glandulifera Royle, whereas I. glandulifera Arn. is a synonym of I. taprobanica Hiern, a native of Sri Lanka (USDA-ARS, 2008).


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I. glandulifera is a tall glabrous annual reaching 50 to 250 cm in height. It is now Europe’s tallest annual species. Its stems can be 0.5 to 5 cm in diameter and are sometimes branched in the upper part. Roots are up to 15 cm deep, the plants often forming numerous adventitious roots from the lower nodes. The leaves are opposite, the upper ones sometimes in whorls of three, up to 25 cm long and 7 cm wide, lanceolate to obovate, petiolate and sharply serrated at the edges. The inflorescences are racemes of 2-14 flowers that are 25-40 mm long. Flowers are strongly zygomorphic, their posterior sepal forming a sac that ends in a straight spur. Their colours vary from white to pink and purple. The capsule is 3-5 cm long and up to 1.5 cm wide. It contains up to 6 (Grime et al., 1988) or 4 to 16 seeds (Beerling and Perrins, 1993), that are 4-7 mm long and 2-4 mm wide with a mean weight of 7.32 mg.

Plant Type

Top of page Annual
Seed propagated


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I. glandulifera is native to the foothills of the Himalayas from north-west Pakistan to northern India. The native range in the western Himalayas is relatively small compared to its invasive range. According to Beerling and Perrins (1993), I. glandulifera is native from Kashmir to Garhwal between 2000 and 2500 masl, and Polunin and Stainton (1984) report the plant can grow up to 4000 masl in its native range. The plant is also recorded as native in Nepal (USDA-ARS, 2008), and possibly in Bhutan.

I. glandulifera is introduced and invasive in much of Europe, and parts of Canada, the USA and New Zealand.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes


IndiaRestricted distributionNative Not invasive Beerling and Perrins, 1993; USDA-ARS, 2008; EPPO, 2014
-Himachal PradeshPresentNative Not invasive Drescher and Prots, 2000; USDA-ARS, 2008; EPPO, 2014
-Jammu and KashmirPresentNativeUSDA-ARS, 2008; EPPO, 2014
-MizoramPresentNativeUSDA-ARS, 2008; EPPO, 2014
-Uttar PradeshPresentNativeWilliamson, 1996; USDA-ARS, 2008; EPPO, 2014
JapanRestricted distributionIntroducedEPPO, 2014
-HonshuPresentIntroducedDrescher and Prots, 2000; EPPO, 2014
NepalPresentNativeUSDA-ARS, 2008; EPPO, 2014
PakistanPresentNative Not invasive Drescher and Prots, 2000; USDA-ARS, 2008; EPPO, 2014

North America

CanadaRestricted distributionIntroducedEPPO, 2014
-British ColumbiaPresentIntroducedUSDA-NRCS, 2008; EPPO, 2014
-ManitobaPresentIntroducedMissouri Botanical Garden, 2008; EPPO, 2014
-New BrunswickPresentIntroducedUSDA-NRCS, 2008
-Newfoundland and LabradorPresentIntroducedUSDA-NRCS, 2008
-Nova ScotiaPresentIntroducedUSDA-NRCS, 2008
-OntarioPresentIntroducedWilliamson, 1996; EPPO, 2014
-Prince Edward IslandPresentIntroducedUSDA-NRCS, 2008
-QuebecPresentIntroducedMissouri Botanical Garden, 2008
-SaskatchewanPresentIntroducedWilliamson, 1996; EPPO, 2014
MexicoPresentUSDA-ARS, 2017Morelos
USARestricted distributionIntroducedEPPO, 2014
-CaliforniaPresentIntroducedUSDA-NRCS, 2008; EPPO, 2014
-ConnecticutPresentIntroducedUSDA-NRCS, 2008
-IdahoPresentIntroducedToney et al., 1998; USDA-NRCS, 2008; EPPO, 2014
-MainePresentIntroducedUSDA-NRCS, 2008; EPPO, 2014
-MassachusettsPresentIntroducedUSDA-NRCS, 2008; EPPO, 2014
-MichiganPresentIntroducedUSDA-NRCS, 2008; EPPO, 2014
-MontanaPresentIntroducedToney et al., 1998; USDA-NRCS, 2008; EPPO, 2014
-New YorkPresentIntroducedToney et al., 1998; USDA-NRCS, 2008; EPPO, 2014
-OregonPresentIntroducedToney et al., 1998; USDA-NRCS, 2008; EPPO, 2014
-Rhode IslandPresentIntroducedEPPO, 2014
-VermontPresentIntroducedUSDA-NRCS, 2008; EPPO, 2014
-WashingtonPresentIntroducedToney et al., 1998; USDA-NRCS, 2008; EPPO, 2014


AustriaWidespreadIntroduced1870s Invasive Drescher and Prots, 2000; Essl and Rabitsch, 2002; EPPO, 2014
BelgiumPresentIntroducedWeber, 2003; EPPO, 2014
BulgariaPresentIntroducedISSG, 2017
CroatiaPresentIntroducedPandza et al., 2001; EPPO, 2014
Czech RepublicWidespreadIntroduced Invasive Pysek and Prach, 1994; Pysek and Prach, 1995; EPPO, 2014
DenmarkPresentIntroducedEPPO, 2002; EPPO, 2014
EstoniaPresentIntroducedISSG, 2017
FinlandWidespreadIntroducedKurtto, 1996; EPPO, 2014
FrancePresentIntroducedEPPO, 2014
-CorsicaAbsent, no pest recordEPPO, 2014
GermanyWidespreadIntroduced Invasive Sebald et al., 1998; Rothmaler et al., 2002; Kowarik, 2003; EPPO, 2014
HungaryPresentIntroducedBalogh, 2001; EPPO, 2014
IrelandPresentIntroducedBeerling and Perrins, 1993; EPPO, 2014
Isle of Man (UK)PresentIntroducedISSG, 2017
ItalyPresentIntroducedISSG, 2017
LatviaPresentIntroducedISSG, 2017
LiechtensteinPresentIntroducedISSG, 2017
LithuaniaPresentIntroducedISSG, 2017
LuxembourgPresentIntroducedISSG, 2017
MacedoniaPresentIntroducedEPPO, 2014; Pacanoski and Saliji, 2014
MontenegroPresentIntroducedISSG, 2017
NetherlandsWidespreadIntroduced Invasive Weeda et al., 1991; EPPO, 2014
NorwayWidespreadIntroducedFremstad and Elven, 1997; EPPO, 2014
PolandWidespreadIntroducedLhotska and Kopecky, 1966; EPPO, 2014
RomaniaPresentIntroducedEPPO, 2014
Russian FederationRestricted distributionIntroducedEPPO, 2014
-Central RussiaPresentIntroducedCzerenov, 1995; EPPO, 2014
-Eastern SiberiaPresentIntroducedCzerenov, 1995; EPPO, 2014
-Russian Far EastPresentIntroducedCzerenov, 1995; Drescher and Prots, 2000; EPPO, 2014
SerbiaPresentIntroducedEPPO, 2014
SlovakiaPresentIntroduced Invasive Eliás, 2001; EPPO, 2014
SloveniaPresentIntroducedEPPO, 2014
SpainPresentIntroducedDana et al., 2001; EPPO, 2014
SwedenWidespreadIntroduced Invasive Beerling and Perrins, 1993; Larson and Martinson, 1998; EPPO, 2014
SwitzerlandWidespreadIntroduced1904 Invasive Sebald et al., 1998; Weber, 2001; EPPO, 2014
UKWidespreadIntroduced1839 Invasive Beerling and Perrins, 1993; Prowse, 1998; EPPO, 2014
-England and WalesPresentIntroducedEPPO, 2014
-Northern IrelandPresentIntroducedEPPO, 2014
-ScotlandPresentIntroducedEPPO, 2014
UkrainePresentIntroducedProtopopova and Shevera, 1998; Protopopova and Shevera, 1998; EPPO, 2014
Yugoslavia (former)PresentIntroducedBeerling and Perrins, 1993


New ZealandPresentIntroducedWebb et al., 1988; EPPO, 2014

History of Introduction and Spread

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I. glandulifera was first introduced to the UK in 1839 as a garden ornamental. Since its introduction to the UK the plant has spread at a rate of 645 km2 per year (Perrins et al., 1993 in Weber, 2003). The spread was enhanced by beekeepers and the general public who released the plant into the wild on many occasions (Rotherham, 2000). The occurrence of I. glandulifera was noticed as early as 1855 in the UK, with the plant being recorded as naturalised in the county of Middlesex. The plant is now recorded throughout the UK including offshore islands such as the Isles of Scilly, the Shetland and Orkney islands.

From the UK I. glandulifera was taken to gardens in many European countries where it is still popular. The plants range expansion in mainland Europe began some 50-100 years later than in the UK. In Finland, the plant was recorded as naturalised in 1947 and individual populations were seen to expand during the 1980s (Kurtto, 1996). In the Czech Republic the earliest record of the plant occurring in the wild was in 1896, in Northern Bohemia (Pysek and Prach, 1995). Garden escapees were found in Switzerland in 1904, from where the species migrated along the Rhine to Germany. Although the explosive mechanism disperses seeds from the plant for only up to 7 m, the invasive spread was fast. Seeds can be transported with rivers over large distances and the spread was helped by humans. The spread is likely to continue with global warming to more northerly or high montane areas (Beerling, 1993).

Risk of Introduction

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Further spread of I. glandulifera is likely. As a result of seed transport with flowing water, it will predominantly lead to an increase in abundance within countries or regions. International transport may be motivated by the ongoing use and promotion of the species as a garden plant. Transport of seeds as a contaminant of soil, building material, etc. is possible, but less likely to cause new introductions (Beerling and Perrins, 1993; Hartmann et al., 1995).

I. glandulifera is regarded as an important invader in several European countries and is on the EPPO list of invasive alien plants, “as posing an important threat to plant health, the environment and biodiversity in the EPPO region. It is on the Swiss 'black list' of harmful invasives (Anon., 2002), listed as invasive in Austria (Essl and Rabitsch, 2002), and is among those invasives in Germany against which specific control measures are directed (Kowarik, 2003). I. glandulifera is also a declared noxious weed in the USA, in Connecticut, Oregon and Washington (USAD-ARS, 2008).


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In Europe, I. glandulifera is predominantly a weed of riparian systems where it can form dense monocultures along river banks (Pysek, 1995; Kowarik, 2003). I. glandulifera is also found in damp natural woodland, where it can attain is maximum known height (up to 3m), in addition the plant is found in forest plantations, forest clearings, railway embankments, waste ground, urban areas, roadside ditches and wet meadows.

In the native range, I. glandulifera is predominately a plant of high altitudes, moist, fertile valleys where it grows in clusters of 30-60 plants mixed in with surrounding native vegetation (Tanner et al., 2008). This is in stark contrast to the dense monocultures found in the invasive, introduced range.

Habitat List

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Disturbed areas Principal habitat Harmful (pest or invasive)
Managed forests, plantations and orchards Secondary/tolerated habitat Harmful (pest or invasive)
Managed grasslands (grazing systems) Secondary/tolerated habitat Productive/non-natural
Rail / roadsides Principal habitat Harmful (pest or invasive)
Urban / peri-urban areas Principal habitat Harmful (pest or invasive)
Natural forests Secondary/tolerated habitat Harmful (pest or invasive)
Natural grasslands Secondary/tolerated habitat Harmful (pest or invasive)
Riverbanks Principal habitat Harmful (pest or invasive)
Wetlands Secondary/tolerated habitat Harmful (pest or invasive)

Hosts/Species Affected

Top of page I. glandulifera is not a weed of agricultural fields. However, native herbaceous plants and tree regeneration can be out-competed by the dense growth of the species (Larson and Martinson, 1998; Maule et al., 2000).


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Biology and Ecology

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The degree of genetic heterogeneity is uncertain, though there is obvious variation in flower colour (Grime et al., 1988). The chromosome number is 2n=18 or 2n=20 (Grime et al., 1988; Beerling and Perrins, 1993).

Physiology and Phenology

Seeds germinate in early spring with a high germination rate of approximately 80% (Sebald et al., 1998). The cotyledon phase lasts until April in the UK when rapid shoot growth begins (Beerling and Perrins, 1993). The root system is augmented by adventitious roots from the lower nodes (Beerling and Perrins, 1993). The time from germination to the onset of flowering is 13 weeks in Germany, with flowering continuing for a further 12 weeks (Sebald et al., 1998). The mortality of seedlings and young plants can be high due to slug predation and physical damage from rainfall and late frosts (Prowse, 1998). Adult plants are killed by the first frost in autumn/winter months.

Reproductive Biology

The self-compatible flowers of I. glandulifera have the highest sugar nectar production per flower than any native European plant species (Chittka and Schürkens, 2001). This enables the plant to attract numerous insect pollinators, especially bees (Apis mellifera), bumble-bees (Bombus spp.) and syrphids. The species is exclusively propagated by seeds. The number of seeds produced is given as 700-800 seeds per plant and 5.7 seeds per pod by Beerling and Perrins (1993), and up to 4000 seeds per plant and 6.4 seeds per pod according to Sebald et al. (1998). A maximum of 32,000 seeds were produced per square metre in a pure stand in Germany (Koenies and Glavac, 1979). Explosive capsules expel seeds from the plant, and dissemination is also aided by flowing water, seeds transported with sediment and the fact that dry seeds are buoyant. In addition, seeds can be spread by human actions, as in the transportation with soil. Seeds require chilling to become viable. Although the species is reported as not having a persistent seed bank (Grime et al., 1988), there are indications that at least some seed can persist for 18 months (Beerling and Perrins, 1993).

Environmental Requirements

I. glandulifera has a preference for high atmospheric humidity. It grows in half-shade but also in full sunlight. In the native range the plant occurs at high altitudes between 1600 and 4300 m, but in Europe it is found at lower elevations. In the UK it has not been found above 210 m and in the eastern Alps in Austria it occurs at up to 1200 m (Drescher and Prots, 2000). In Europe, plants of all ages are frost intolerant with adults killed by the first frost in autumn and seedlings by late frosts in spring (Sebald et al., 1998). The species is also drought-intolerant and quickly wilts, and plants can survive only if the drought period is short (Beerling and Perrins, 1993). As an annual, the species is dependent on open sites for germination each spring; it is consequently favoured by disturbance. It occurs on a wide spectrum of soils from nutrient-poor to nutrient-rich and grows on mineral soils as well as on peat (Kowarik, 2003).


I. glandulifera is found in five main community types, riparian habitats, fens, mesotrophic grasslands, waste ground and woodlands. Within each habitat few associated plant species have been recorded growing within monocultures of the plant. In the UK, the main associated species are similar across the community types, and include Rubus fruticosusUrtica dioica,Galium aparine, Cirsium arvense, and in wooded habitats the plant grows under a variety of tree species.

In southern Germany, it is most often accompanied by Urtica dioica, Aegopodium podagraria, Lamium maculatum and Galium aparine (Oberdorfer, 1983). Dense riverbank vegetation with I. glandulifera was described as Impatienti-Calystegietum, e.g., along the Odra in Poland (Dajdok et al., 1998).


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C - Temperate/Mesothermal climate Preferred Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C
Cf - Warm temperate climate, wet all year Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
0 4300

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) -9 0
Mean annual temperature (ºC) 5 18
Mean maximum temperature of hottest month (ºC) 10 30
Mean minimum temperature of coldest month (ºC) -5 5


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ParameterLower limitUpper limitDescription
Dry season duration01number of consecutive months with <40 mm rainfall
Mean annual rainfall5002000mm; lower/upper limits

Rainfall Regime

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Soil Tolerances

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Soil drainage

  • free
  • impeded

Soil reaction

  • acid
  • alkaline
  • neutral
  • very acid

Soil texture

  • heavy
  • light
  • medium

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Aphis fabae Herbivore not specific Beerling and Perrins, 1993
Deilephila elpenor Herbivore not specific Beerling and Perrins, 1993
Impatientinum balsamines Herbivore not specific Beerling and Perrins, 1993
Siobla sturmi Herbivore Schmitz, 2007
Xanthorhoe biriviata Herbivore Schmitz, 2007

Notes on Natural Enemies

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I. glandulifera supports an impoverished diversity of phytophagous insects in the UK, but the extent to which these affect the ecology of the plant is not sufficiently studied (Beerling and Perrins, 1993). In the UK, only 3 arthropod species are known to feed on I. glandulifera, including two aphid species, Aphis fabae and Impatientinum balsamines, and the elephant hawk moth Deilephila elpenor (Beerling and Perrins, 1993).

Means of Movement and Dispersal

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Natural Dispersal

Seeds are expelled from the plant by explosive dehiscence of the capsule and can lead to dispersal distances of 7 m. Long-distance dispersal of seeds occurs with the aid of flowing water such as along rivers. Fresh seeds are transported with sediment on the beds of rivers, and dry seeds are buoyant and can float over large distances.

Vector Transmission 

Isolated observations of seeds dispersed up to 10 m from the mother plant may indicate the possibility of seed transport by small rodents (Beerling and Perrins, 1993).

Accidental Introduction

Transport with topsoil is probable (Beerling and Perrins, 1993) but it is not clear, however, to what extent this has occurred in the introduction or spread to new areas. The transport of seed with river gravel in trains was reported in Germany (Hartmann et al., 1995), as well as contamination of building rubbish transported to waste disposal sites.

Intentional Introduction

I. glandulifera was imported as an ornamental species for its showy and scented flowers. It is being used as a garden plant in many European countries and is still sold by seed companies (Beerling and Perrins, 1993). The general public have aided the transport of this species throughout the UK, deliberately planting seeds in hedgerows and grassland (Rotherham, 2000). The flowers are very rich in pollen, and bee-keepers have dispersed seeds in order to enhance forage for honey bees (Hegi, 1912; Hartmann et al., 1995).

Plant Trade

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Plant parts liable to carry the pest in trade/transportPest stagesBorne internallyBorne externallyVisibility of pest or symptoms
Growing medium accompanying plants seeds
Stems (above ground)/Shoots/Trunks/Branches Pest or symptoms usually visible to the naked eye
True seeds (inc. grain) seeds
Plant parts not known to carry the pest in trade/transport
Fruits (inc. pods)
Seedlings/Micropropagated plants

Economic Impact

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The UK Environment Agency have estimated it would cost between £150-300 million to eradicate I. glandulifera from the UK should such a control programme be initiated. In Switzerland, Gelpke and Weber (2005) estimated it would cost between CHF 2,183,500 and CHF 13,812,696 (£923,133 to £5,839,691) to eradicate 95% of the current population of I. glandulifera in the Canton of Zürich alone. Such high costs coupled with the difficulty of implementing catchment scale control programmes due to the division of land makes controlling I. glandulifera on a national or regional level virtually impossible. Current control methods are labour intensive and difficult to implement also due to the often inaccessible habitats in which I. glandulifera grows. Control costs range from £0.50/m2 for a single chemical application, or manual control by strimming up to £10/m2 when habitat restoration is included (Tanner et al., 2008).

Environmental Impact

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Impact on Habitats
I. glandulifera can lead to increased erosion of riverbanks as it leaves soils bare when it dies back in winter. However, this is not well proven by evidence, as the species is often integrated in perennial vegetation. The exclusion of other plants from the vegetation, however, is not as complete as in the case of other invasive species. This is due to the fact that I. glandulifera, as an annual, is not present in the vegetation for the whole growing season. It germinates in spring and reaches dominance in the summer. Plants completing their life cycle in spring or early summer are consequently little affected by the species. In addition, the dominance reached by I. glandulifera may vary from year to year according to the weather conditions in the germination phase. The effect on other plants consists of a change in cover/dominance. 
Plant soil feedback experiments conducted by Pattison et al. (2016) found that I. glandulifera grew both larger and faster in soil conditioned by this species. In addition to this they found that I. glandulifera not only lowers the abundance of arbuscular mycorrhizal fungi in the soil but also increases foliar endophytes, which may protect the plant from herbivory (Pattison et al., 2016). 
Impact on Biodiversity
I. glandulifera has the potential to impact on both native flora and fauna, though further research is required. I. glandulifera was shown to reduce native species diversity by 25% in areas where it forms monocultures (Hulme and Bremner, 2005). The synchronous germination of the plants population along riverbanks and its vigorous growth rates can shade out local native species and reduce the available niches for native species growth. Plant species growing in similar habitats to that of I. glandulifera often have reduced in vigour and cover due to the superior competitive strength of I. glandulifera
I. glandulifera, with its nectar-rich and scented flowers attracts many more pollinators than native plants, and thus has a negative effect on the fitness of the natives (Chittka and Schürkens, 2001). Over time, such competition between plant species for pollinators could leave native species which are unsuccessful at attracting pollinators genetically depauperate (Prowse and Goodridge, 2000).
The impact on invertebrate species is even less clearly defined. The rich nectar production may support some invertebrate groups and infestations with aphids supports a food-chain of aphidophagous arthropods. On the other hand, the displacement of food plants may reduce mono- or oligophagous insects. When the plant invades riparian habitats, specifically exposed riverine sediments, the occurrence of I. glandulifera can potentially reduce the available niches for ground beetles endemic to those habitats (Hymen, 1992). A detailed study on above and below ground invertebrates by Tanner et al., (2013) found that in I. glandulifera invaded plots, species richness of Coleoptera and Heteroptera in the foliage reduced significantly and ground dwelling herbivores, detritivores and predators were less abundant. They concluded that as a result this could lead to a less diverse habitat with implications on higher trophic levels (Tanner et al., 2013).

Social Impact

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Although social impacts are difficult to quantify, the fact that I. glandulifera can restrict access to rivers for recreation and other amenities should be noted.

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Abundant in its native range
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Pioneering in disturbed areas
  • Tolerant of shade
  • Highly mobile locally
  • Fast growing
  • Has high reproductive potential
  • Gregarious
  • Has propagules that can remain viable for more than one year
Impact outcomes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Modification of successional patterns
  • Monoculture formation
  • Negatively impacts forestry
  • Reduced amenity values
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Competition - monopolizing resources
  • Competition - shading
  • Competition - smothering
  • Rapid growth
Likelihood of entry/control
  • Highly likely to be transported internationally deliberately
  • Difficult/costly to control


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I. glandulifera is used as a garden ornamental and as a honey plant. It produces flowers with high nectar content and acts as a late source of nectar for bees and butterflies. Cattle are known to feed on the whole plant (Beerling and Perrins, 1993) but the browse value is not known.

Similarities to Other Species/Conditions

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Other Impatiens species are somewhat similar but differ in conspicuous features: The Asian I. parviflora is much smaller and has small pale-yellow flowers. Also, the yellow flowered European I. noli-tangere and the orange flowered American I. capensis are both smaller morphologically. The garden ornamental I. balsamina that occasionally escapes to waste ground in North America and in Europe has pubescent stems and capsules and usually single flowers.

Prevention and Control

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SPS Measures

In the UK I. glandulifera is listed in the Schedule 9 Wildlife and Countryside Act 1981. This means that it is an offence to plant I. glandulifera or allow it to grow in the wild (GB Non-native species secretariat, 2017). 

Cultural Control

I. glandulifera is not resistant to grazing or cutting. Maintaining traditional forms of land-use in grassland will prevent invasion into such vegetation. Mowing and grazing can also be successful in eliminating existing infestations though this would need repeating annually and on a catchment scale.

Mechanical Control

As an annual, and in discrete areas, I. glandulifera can be more easily controlled than perennial invasive plants. Any control must aim at preventing the plants from setting seed. Best results are achieved by applying mechanical control late in the season, i.e. when the plants are in flower or beginning to flower. Early cutting of the plants below the first node can control populations though this is labour intensive. In Germany, several mechanical methods have been tested (Hartmann et al., 1995), and mowing with or without removal of the plant material, mulching or soil cultivation have all been successful. In larger stands and where soil conditions permit, agricultural machinery may be used. Where the soil is wet and soft, heavy machinery will damage the soil and provide open spaces ideal for re-establishment. In smaller stands, hand-held brush cutters can be used and hand-pulling of the plants is also feasible. In such cases, care has to be taken that pulled plants find no chance to re-grow where they are deposited. For lasting success, the area should be monitored for re-growth.

Chemical Control

Both selective herbicides such as 2,4-D and triclopyr, and non-selective herbicides such as glyphosate were found suitable in controlling I. glandulifera. According to the locally applicable law, a permit may be required to use herbicides, in particular near water.

Biological Control

Since 2006, research has been conducted on the biological control of I. glandulifera, where numerous surveys for natural enemies have been conducted throughout the plants native range (India and Pakistan). Due to the high level damage observed in the field, the rust fungus Puccinia komarovii was prioritised for further study. Cross inoculation studies revealed a high level of specificity of this rust towards I. glandulifera and as such, the rust was renamed as a variety, P. komarovii var. glanduliferae (Tanner et al., 2014). Experiments were conducted to determine the lifecycle of the rust and revealed that it is macrocyclic (has all five spore stages) and is autoecious (completes its lifecycle on I. glandulifera only) (Tanner et al., 2015). Host-specificity testing assessed 75 non-target plant species including several varieties of selected species and proved that the rust is a true specialist to its natural host I. glandulifera (Tanner et al., 2015). A Pest Risk Assessment (PRA), which fully detailed the research conducted on the host-range, lifecycle and ecology of the rust was submitted to FERA in 2014; this was followed by a public consultation. The PRA underwent further evaluation by the European Commission’s Standing Committee on Plant Health and following their feedback Defra Ministers approved the release of an isolate from India in July 2014. Since then, the rust has been released at selected sites in England and Wales. Further details of rust releases in the UK can be found in Varia et al. (2016).

Biotype inoculation experiments undertaken at CABI have shown that the susceptibility of I. glandulifera to the rust can vary dramatically between individual populations of I. glandulifera even when grown under the same environmental conditions. For example, susceptible populations (supporting successful sporulation of the rust) and populations that are completely resistant (no symptoms of infection) to the rust have been identified (Varia et al., 2016). A molecular study by Nagy and Korpelainen (2015) concluded that there have been multiple introductions of I. glandulifera from both Pakistan and India into the UK. As rust fungi are highly host specific, it is believed that different strains of the rust exist which have evolved with distinct biotypes of the plant. As such, a strain from Pakistan is currently being assessed against UK populations of I. glandulifera and results show that it infects a different range of UK populations to the strain from India (Varia et al., 2016). Permission to release this strain from quarantine was approved by Defra in January 2017 and this strain will be trialled in the field at selected sites during 2017.

Integrated Control

Integrated control must aim at maximizing the control effect while minimizing environmental side effects. Due to the downstream transportation of seeds, control measures in the catchment area of a river must start at the upper reaches and move on downstream. However, this is often impossible due to the division of land ownership and high associated costs.

Ecosystem Restoration

Tanner and Gange (2013) suggested that after the removal of I. glandulifera from an area, to prevent re-establishment and colonisation by other non-native species, native species should be reintroduced to promote arbuscular mycorrhizal fungi which have been depleted.


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Links to Websites

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Himalayan Balsam Knowledge Centre


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29/03/17 Updated by:

Kate Pollard, CABI, Egham, Surrey, UK 

26/05/2008 Updated by:

Rob Tanner, CABI, Egham, Surrey, UK

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