Black locust, false acacia	Status LU: established. 1st record: LU 1787, ITW <1836.
	Schäinakazi	Status Eur.: established. 1st record: FR 1602.1
	Robinier faux-acacia, acacia	RA: ISEIA: A3, Black List. Harmonia+: 0,53.
	Gewöhnliche Robinie, Falsche Akazie	Wikipedia: | Wikispecies: | CABI
	Robinia, valse acacia	Back to the list of neophytes

Brief description

Robinia pseudoacacia L. is an early successional plant, preferring full sun, well drained soils, and little competition. It reproduces both from seed and by sprouting from the roots or stump. Although this tree produces abundant seeds, germination rate is often low in our climatic conditions [Belgium]. The area potentially invaded is likely to increase considerably under a warmer climate. Once introduced, the black locust expands readily by root suckering and stump sprouting and forms dense clones creating shaded islands from which most native plants are outcompeted. It also modifies soil properties and favours the development of a nitrogen-demanding vegetation. The large, fragrant blossoms of R. pseudoacacia are sometimes reported to compete with native plants for pollinating bees (Branquart et al. 2015).

Originally from North America, Robinia pseudoacacia was introduced to Europe at the beginning of the 17th century by Jean Robin (1550-1629), the French court gardener. One of the first European black locust trees, now over 400 years old, is still standing in Paris, near Notre-Dame (Anonymous 2020: 8). It is standing on square René-Viviani and is to date the oldest tree of Paris (Baraton 2021: 353).

Status and distribution in Luxembourg

Tinant (1836: 371) mentions “Robinia Pseudo-Acacia” as a naturalised exotic tree.

In 1860, Eugène Fischer reports that Jean-Mathias de Blochausen brought back several tree species from a journey to Italy in 1669, including false acacia and Italian poplar, the latter for roadside planting (Fischer 1860: 178-181).² Around 1872, according to the same Eugène Fischer (1872: 37-38), “it is frequently and advantageously cultivated on our slopes, poor iridescent marls, in groves, promontories, and it is sometimes even used to make fence hedges. The first Robinia trees planted in the Grand Duchy were imported from Italy around 1669 by a de Blochausen. For more than a century this tree was still rare in the country, since Mr. de la Fontaine, former governor of the Grand Duchy, mentioned, as one of the first subjects of this tree in our country, an acacia tree planted in 1787 by Mr. Baron de Maréchal in the garden dependent on Stadtbredimus castle”.³ (see also: Fontaine 1862: 89; Klein 1897: 432).

This year, 1669, mentioned by Fischer, appears to be an error: the facts related are dated in the wrong century as the Family de Blochausen only arrived in Luxembourg around 1764, when Marie-Gisberte de Blochausen bought the Domaine de Brückenberg in Colmar-berg and Jean-Mathias de Blochausen bought the Rollingen forge. We therefore guess that it should read 1769 instead of 1669, which would also be in line with two reports of first planting in 1787 in Stadtbredimus (Fischer 1872: 37-38) and at Kaaschtel near Altwies (Commune de Mondorf 2013, Wikipedia Luxembourg 2013). So we consider 1787 as the year of first record in Luxembourg until historic research brings new evidence.
One of the oldest black locust trees of Luxembourg can be admired in the village of Tétange, municipality of Kayl. The multi-stem tree has a diameter of 150 cm (Anonymous 2020: 9).

Oldest herbarium specimens at the MNHNL:

• June 1883: Edmond Joseph Klein (1866-1942) collected a specimen in the district Pulvermühl in Luxembourg City (Specimen № 16553, MNHNL 2000-)
• 24 May 1934: J. Witry collected a specimen in Rumelange (Specimen № 51811, MNHNL 2000-)
• 18 May 1952: Marcel Etringer collected a specimen in Groeknapp in Graulinster, municipality of Junglinster (Specimen № 49906, MNHNL 2000-)

1346 records are accessible through the MNHNL-mdata portal (MNHNL, iNaturalist & GBIF 2019).

False acacia is a common ornamental tree in Luxembourg, and also occurs widely in the wild, mostly along roadside slopes and railway lines. The distribution map does not reflect the real distribution in the country: the species is so widespread that it is hardly reported any more. An inventory in 2013 revealed the false acacia to be one of the most common invasive alien vascular plant species along railways (Pfeiffenschneider et al. 2014b).

Until 2013 black locust was not considered an invasive alien species in Luxembourg by the Nature Conservation and Forestry Administration (Administration de la nature et des forêts – ANF).

Miscellaneous

• The false acacia plays a role in honey production in Luxembourg.
• Except for its flowers, black locust is highly poisonous, which is why black locust wood should not be used for grilling (Anonymous 2020: 9).
• Acacia wood is used for various purposes: it is sought after for resistance parts, tool handles, etc. Its leaves provide excellent forage and its flowers are gleaned by bees (Krombach 1875: 115).⁴
• Next to the Kaaschtel, a former oppidum across the French border southeast of Altwies on former Luxembourg territory in Lorraine, France, a few huge and very old individuals of Robinia can be found. A legend says the Lord of Preisch brought them from a pilgrimage to the Holy Land and had them planted in 1787 (Commune de Mondorf 2013, Wikipedia Luxembourg 2013).

Other Robinia cultivars and taxa

• The flowerless cultivar ‘Umbraculifera’ has been cultivated in Luxembourg for a long time (Koltz 1873: 43; 1875) and is quite common all across the country (Welter et al. 2008: 72). A beautiful example can be seen in the court of the National Centre of Literature in Mersch.⁵ Koltz (1873: 43) lists Robinia pseudo-acacia var. umbraculifera Des. as a variety (Fr: Acacien boule). According to Krombach (1875: 115) the cultivar ‘Umbraculifera’ (Fr: Acacia parasol) was grown in gardens under the French names of “Acacia boule” or “Acacia fourrage”.
• Recently there has been an increase in the cultivar ‘Unifoliola’, as more street and alignment trees have been observed (Welter et al. 2008).
• Robinia viscosa Vent., another North American species, is very rare in Luxembourg (Welter et al. 2008).
• Lambinon & Verloove (2012: 392) mention cultivated less spiny and less flowering intraspecific taxa, that can be combined under the name Robinia pseudoacacia var. inermis; furthermore some other pink-flowered representatives of the genus Robinia are sometimes grown for ornamental purposes in parks and especially along avenues, including R. ×ambigua Poiret (R. pseudoacacia × viscosa Vent.) and R. hispida L..
• Koltz (1873: 43) lists Robinia viscosa Vent. (Fr: Acacien [sic!] rose). Krombach (1875: 115) mentions R. viscosa with viscous branches and pink flowers in short bunches.

Risk assessment

ISEIA protocol

A3 (2+3+3+3) = Black List (Ries et al. 2013: 19).

Harmonia+ protocol

Overall risk score 0,53 = (Overall Invasion score 0,89 x Overall Impact score 0,60) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Anonymous, 2020. Baum des Jahres 2020: Die Robinie. Regulus 5 (2020): 8-9.
• Baraton, A., 2021. Dictionnaire amoureux des arbres. Plon. 438 pp.
• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum & F. Verloove, 2015. Harmonia database: Robinia pseudoacacia L. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-23]
• CABI, 2019. Robinia pseudoacacia. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2020-03-02]
• Commune de Mondorf, 2013. Le Castel – De Kaaschtel. URL: http://www.mondorf.info/index.php?option=com_content&view=article&id=17&Itemid=86&lang=fr [2013-09-27].
• Fischer, E., 1860. Notices historiques sur la situation agricole du grand-duché de Luxembourg. 2e édition, 254 p. Luxembourg : imprimerie Buck.
• Fischer, E., 1872. Les plantes subspontanées et naturalisées de la flore du grand-duché de Luxembourg. Publications de l’Institut royal grand-ducal de Luxembourg, section des sciences naturelles et mathématiques XII: 1-115. Imprimerie V. Buck, Luxembourg.
• Fontaine, G.T. I. de la, 1862. Robinier – Acacia. Bull. Soc. sci. nat. g.-d. Luxemb. 5 (1857-1862): 89.
• Klein, E. J., 1897. Die Flora der Heimat (sowie die hauptsächlichsten bei uns kultivierten fremden Pflanzenarten biologisch betrachtet. Eine Anleitung zur selbständigen Beobachtung der Lebens- und Anpassungserscheinungen in der Pflanzenwelt). 552 S., Buchdruckerei Justin Schroell, Diekirch.
• Koltz, J.-P.-J., 1873. Prodrome de la flore du grand-duché de Luxembourg. Première partie. Plantes phanérogames. Imprimerie V. Buck, Luxembourg. 279 S.
• Koltz, J.-P.-J., 1875. Dendrologie luxembourgeoise. Catalogue des arbres, arbrissaux et arbustes spontanés, subspontanés ou introduits dans les cultures du Grand-Duché de  Luxembourg. Imprimerie de V. Buck, Luxembourg.
• Krombach, J.-H.-G., 1875. Flore du grand-duché de Luxembourg. Plantes phanérogames. 564 p. Luxembourg, Imprimerie Joris.
• Lambinon J. & F. Verloove, 2012. Nouvelle flore de la Belgique, du grand-duché de Luxembourg, du Nord de la France et des régions voisines. Sixième édition. Avec la collaboration de L. Delvosalle, B. Toussaint, D. Geerinck, I. Hoste, F. Van Rossum, B. Cornier, R. Schumacker, A. Vanderpoorten et H. Vannerom. Jardin botanique national de Belgique, Meise. CXXXIX + 1195 pp. ISBN : 9789072619884.
• MNHNL, 2000-. Robinia pseudoacacia L. in Recorder-Lux, database on the natural heritage of the Grand Duchy of Luxembourg. Musée national d’histoire naturelle, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-09-05]
• MNHNL, iNaturalist & GBIF, 2019. Robinia pseudoacacia L. in MNHNL-mdata, online portal combining species observation from Recorder-Lux, iNaturalist and GBIF. National Museum of Natural History, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-09-06]
• Pfeiffenschneider, M., P. Gräser & C. Ries, 2014a. Distribution of selected neophytes along the main rivers of Luxembourg. Bull. Soc. Nat. luxemb. 115: 101-108. [PDF 3668 KB]
• Pfeiffenschneider, M., P. Gräser & C. Ries, 2014b. Distribution of selected neophytes along the national railway network of Luxembourg. Bull. Soc. Nat. luxemb. 115: 95-100. [PDF 1457 KB]
• Ries, C. & Y. Krippel, 2021. First records of 56 invasive alien vascular plants in Luxembourg. Bulletin de la Société des naturalistes luxembourgeois 123: 115-127. [PDF 241 KB]
• Ries, C., Y. Krippel & M. Pfeiffenschneider, 2020. Risk assessment after the Harmonia+ protocol of invasive alien vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 122: 197-205. [PDF 132 KB]
• Ries, C., Y. Krippel, M. Pfeiffenschneider & S. Schneider, 2013. Environmental impact assessment and black, watch and alert list classification after the ISEIA Protocol of non-native vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 114: 15-21. [PDF 652 KB]
• Schneider, N. & T. Walisch, 2009. Sur la présence au Luxembourg d’Obolodiplosis robiniae (Haldeman, 1847) (Insecta, Diptera, Cecidomyiidae). Bull. Soc. Nat. luxemb. 110: 161-166.
• Tinant, F. A., 1836. Flore luxembourgeoise, ou, Description des plantes phanérogames, recueillies et observées dans le grand-duché de Luxembourg, classées d’après le système sexuel de Linnée. 512 p. Luxembourg, J. P. Kuborn.
• Welter A., J. Turk & J. Trossen, 2008. Les arbres introduits au Luxembourg. Inventaire des essences arborescentes non indigènes de pleine terre présentes sur le territoire du Grand-Duché de Luxembourg. Ferrantia 53, Musée national d’histoire naturelle, Luxembourg, 111 p. [pdf 9,9 MB]
• Wikipedia Luxembourg, 2013. Kaaschtel. URL: http://lb.wikipedia.org/wiki/Kaaschtel [2013-09-27].

 Page content last updated on 2021-08-04. Last proofread by Caroline Grounds on 2019-11-21.

1. Baraton 2021: 353. CABI 2019 mentions 1604.[↩]
2. ”Il paraît que les premiers peupliers d’Italie plantés dans le Grand-Duché, l’ont été sur le domaine de Berg vers 1669, où ils avaient été apportés d’Italie par Jean-Mathias de Blochausen. Ce dernier les a importés lors d’un voyage qu’il a fait en Italie, et à l’occasion duquel il a aussi introduit les premiers acacias dans le pays.”[↩]
3. Original text: “Il est fréquemment et avantageusement cultivé sur nos talus, les marnes irisées pauvres, dans les bosquets, les promeandes, et il sert même quelquefois à faire des haies de clôture. Les premiers sujets de robinier plantés dans le Grand-Duché ont été importés d’Italie vers 1669 par un de Blochausen. Pendant plus d’un siècle cet arbre était encore rare dans le pays, attendu que M. de la Fontaine, ancien gouverneur du Grand-Duché, a cité comme l’un des premiers sujets de cet arbre chez nous, un acacia planté en 1787 par M. le baron de Maréchal dans le jardin dépendant du château de Stadtbredimus.” (Fischer 1872: 37-38).[↩]
4. Original text: “Le bois d’acacia sert à divers usages: il est recherché pour pièce de résistance, manches d’outils etc. Ses feuilles donnent un excellent fourrage et ses fleurs sont butinées par les abeilles” (Krombach 1875: 115).[↩]
5. Address: Centre national de littérature, 2, rue Emmanuel-Servais, L-7565 Mersch. http://www.cnl.public.lu [↩]

	Giant knotweed, Sakhalin knotweed	Status LU: established. 1st record: LU & ITW 1959.
	Sachalin-Knuetkraut	Status Eur.: established. 1st record: UK 1860s.
	Renouée de Sakhaline	RA: ISEIA: B1 – Watch List. Harmonia+: 0,59.
	Sachalin-Staudenknöterich, Riesen-Knöterich	Wikipedia: | Wikispecies: | CABI
	Sachalinse duizendknoop	Back to the list of neophytes

Brief description

Like other Asiatic knotweeds, Fallopia sachalinensis (F. Schmidt Petrop.) Ronse Decr. colonises a wide range of environments, with a predilection for moist and nitrogen-rich soils. It prefers sunny places or semi-shaded habitats. This pioneer plant proliferates both in ruderal and semi-natural habitats, including riparian areas and open forests. Stem and rhizomes may easily split into small pieces; fragments are able to regenerate a plant, provided a node is present. Giant knotweed produces a small number of viable seeds, but seedlings are seldom observed in the wild. Transport of garden waste and soil contaminated with rhizomes are the major dispersal modes. Where the plant is widely consolidated on river banks it is also spread by floods and can easily colonise downstream.

Fallopia sachalinensis is able to monopolise space and to form dense and persistent populations. It can outcompete most of native herbaceous plant species thanks to early seasonal development, high growth rate and productivity, abundant leaf cover, allelochemical production and clonal spread associated with an extraordinarily high rate of proliferation of below-ground organs. It can even outcompete Fallopia japonica on alluvial riverbanks. Its development reduces plant and invertebrate species diversity, alters habitats for fish and wildlife, change light and energy conditions of the ecosystem, and favours river bank erosion during the winter. It can also break through tarmac and thin layers of concrete, and can penetrate some flood defences (Branquart et al. 2011).

Status and distribution in Luxembourg

Fallopia sachalinensis (F. Schmidt Petrop.) Ronse Decr. was first documented on 14th May 1959 in Lëtschet (Municipality of Steinsel) by Léopold Reichling (1921-2009) (MNHNL 2000-).

108 records of this melliferous species are listed in the MNHNL-mdata online portal (MNHNL, iNaturalist & GBIF 2019).

Giant knotweed is less common and less widespread in Luxembourg than its relatives Bohemian knotweed (Fallopia ×bohemica), and Japanese knotweed (Fallopia japonica). It sometimes builds huge colonies along riparian ecosystems, as can be seen along the river Alzette in Luxembourg City (beside the Neumünster Abbey in the Grund district) and along the Sûre east of Diekirch. It is mostly found as an ornamental plant in private gardens. Populations in the wild are the result of people fly-tipping their knotweed clippings.

Sometimes grown for ornamental purposes in parks. Naturalised here and there: rare. The frequency of male-sterile and male-fertile colonies, distinguishable by the morphology of the inflorescence, should be specified (Lambinon & Verloove 2012: 193).

Risk assessment

ISEIA protocol

B1 (2+2+3+3) = Watch List (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,59 = (Overall Invasion score 0,84 x Overall Impact score 0,70) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Albers, M., S. Kohn, J. Steng & M. Pfeiffenschneider, 2001. – Problematik der Bioinvasion. Kartierung von Japan-Knöterich, Riesenbärenklau und Indischem Springkraut an Woltz, Clerve und Wiltz. Ergebnisse der Kartierung. – Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, arrondissement nord. August 2001. 7S. + Anhang.
• Bailey, J.P. & A.P. Conolly, 2000. Prize-winners to pariahs – A history of Japanese Knotweed s.l. (Polygonaceae) in the British Isles. Watsonia. 23: 93–110.[PDF]
• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum, F. Verloove & A. Vervoort, 2011. Harmonia database: Fallopia sachalinensis (F. Schmidt Petrop.) Ronse Decr. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-11]
• CABI, 2019. Fallopia sachalinensis. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2020-03-02]
• Glesener, B., M. Pfeiffenschneider & C. Ries, 2009. Die Verbreitung von Impatiens glandulifera, Fallopia japonica, F. sachalinensis, F. ×bohemica und Heracleum mantegazzianum entlang der Hauptfließgewässer Luxemburgs. Bull. Soc. Nat. luxemb. 110 : 69-73. (pdf)
• Lambinon J. & F. Verloove, 2012. Nouvelle flore de la Belgique, du grand-duché de Luxembourg, du Nord de la France et des régions voisines. Sixième édition. Avec la collaboration de L. Delvosalle, B. Toussaint, D. Geerinck, I. Hoste, F. Van Rossum, B. Cornier, R. Schumacker, A. Vanderpoorten et H. Vannerom. Jardin botanique national de Belgique, Meise. CXXXIX + 1195 pp. ISBN : 9789072619884.
• MNHNL, 2000-. Fallopia sachalinensis (F. Schmidt Petrop.) Ronse Decr. in Recorder-Lux, database on the natural heritage of the Grand Duchy of Luxembourg. Musée national d’histoire naturelle, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-10-11]
• MNHNL, iNaturalist & GBIF, 2019. Fallopia sachalinensis (F. Schmidt Petrop.) Ronse Decr. in MNHNL-mdata, online portal combining species observation from Recorder-Lux, iNaturalist and GBIF. National Museum of Natural History, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-10-11]
• Pfeiffenschneider, M., 2001. – Problematik der Bioinvasion. Nationales Inventar von Riesenbärenklau, Indischem Springkraut und exotischen Knötericharten. Ergebnisse einer Umfrage und Konzept zur Bekämpfung der Riesenbärenklaubestände. – Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, Service de la conservation de la nature, November 2001. 23 S. + Anhang, Luxembourg.
• Pfeiffenschneider, M., 2007. Über die Verbreitung von Heracleum mantegazzianum, Impatiens glandulifera, Fallopia japonica und F. sachali­nensis entlang der Gewässer Obersauer, Woltz, Clerve, Wiltz und ihrer Nebengewässer (Luxemburg). Bull. Soc. Nat. luxemb. 108 : 7-10. (pdf)
• Pfeiffenschneider, M., 2008. Neophyten in Luxemburg – Projekt Bioinvasion 2007. Arbeitsbericht. 18 S. (pdf)
• Pfeiffenschneider, M. & M. Owaller, 2000. – Kartierung von Japan-Knöterich, Riesenbärenklau und Indischem Springkraut an der Obersauer. Theoretische Grundlagen und Ergebnisse der Kartierung.. – Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, acrrondissement nord. August 2000. 37S. + Anhang, Luxembourg.
• Ries, C. & Y. Krippel, 2021. First records of 56 invasive alien vascular plants in Luxembourg. Bulletin de la Société des naturalistes luxembourgeois 123: 115-127. [PDF 241 KB]
• Ries, C., Y. Krippel & M. Pfeiffenschneider, 2020. Risk assessment after the Harmonia+ protocol of invasive alien vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 122: 197-205. [PDF 132 KB]
• Ries, C., Y. Krippel, M. Pfeiffenschneider & S. Schneider, 2013. Environmental impact assessment and black, watch and alert list classification after the ISEIA Protocol of non-native vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 114: 15-21. [PDF 652 KB]

 Page content last updated on 2021-04-12. Last proofread by Caroline Grounds on 2019-11-18.

	Himalayan Balsam	Status LU: established. 1st record: LU <1897, ITW 1958.
	Drüse-Sprangkraut	Status Eur.: established. 1st record: UK 1839.1 IAS of EU concern (2017).
	Impatiente de l’Inde, balsamine de l’Himalaya	RA: ISEIA: A3, Black List. Harmonia+: 0,52.
	Drüsiges Springkraut, Indisches S., Emscherorchidee	Wikipedia:  | Wikispecies: | CABI
	Reuzenbalsemien	Back to the list of neophytes

Brief description

Impatiens glandulifera Royle occurs in many different habitats, but it thrives best on moist and nutrient-rich alluvial soils. It occurs on meadows, along rivers and brooks, and in floodplain forests, especially in areas disturbed by people. Long-distance dispersal of seeds is aided by flowing water, with fresh seeds transported in sediment on the beds of rivers, and buoyant dry seeds are able to float over large distances. The species may form dense stands that cover the soil, shade and replace native annual and even perennial plant species because of early germination and rapid growth. In some conditions, it can strongly reduce local species richness but this reduction is often temporary and concerns mostly widespread weeds and even other non–native species in ground-water table and flooding conditions. It may also displace native species through competition for pollinators, e.g. Stachys palustris. Its development can facilitate river bank erosion (Branquart et al. 2010).

IAS of Union concern

In 2017, Impatiens glandulifera was added to the list of invasive alien species of Union concern (Anonymous 2017) which implies that member states shall take all necessary steps to prevent it’s unintentional introduction or spread.

For Luxembourg, an action plan in accordance with Article 13(2) of Regulation 1143/2014 (Anonymous 2014a) has been finalised in 2020 (Pfeiffenschneider & Hoppe 2020).

Status and distribution in Luxembourg

Impatiens glandulifera Royle was first mentioned in Luxembourg under its synonym Impatiens glanduligera (Royle) as cultivated ornamental in the flora of Klein (1897: 249).

Impatiens glandulifera Royle was first documented in the wild under its synonym Impatiens roylei Walp. on 1958-10-06 by Jean-Jacques Kariger (1925-2018) in Hautcharage (Kariger 1961: 101, Krippel & Proess 2017). The next record was made by Léopold Reichling (1921-2009) on 4th August 1966 in Koetschette, municipality of Rambrouch (MNHNL 2000-).

With over 7.500 records of the species listed in the MNHNL-mdata online portal (2024), the species is established in Luxembourg and widespread throughout the country’s riparian ecosystems (MNHNL, iNaturalist & GBIF 2024). Most of these data have been collected during systematic inventories along the main watercourses in 2006-2008 (Glesener et al. 2009), 2013 (Pfeiffenschneider et al. 2014) and 2019.

The melliferous Himalayan balsam is one of the most common and widespread invasive neophytes in Luxembourg. It builds huge colonies along riparian ecosystems, often together with colonies of Bohemian knotweed. Several major rivers of Luxembourg are being affected. Huge populations can for example be seen along the river Sure between Ettelbruck and Michelau.

Spread into forest ecosystems

Since the end of the first decade of the 21st century, Himalayan balsam is increasingly spreading throughout the countryside, leaving the riverbanks and colonising other habitats like roadsides and forests. An example can be seen in the Our valley between Stolzembourg and Dasbourg-Pont, where the Himalayan Balsam managed to “jump” across the main road, to “climb” up the steep slopes and to “enter” the oak forests. Meanwhile Impatiens glandulifera occurs in many forests across the country.

Recent new records have confirmed that this invasive species is increasingly being observed far from any watercourse, often at the edge of forests (Krippel et al. 2020: 39).

Over the past 20 years, the dissemination of I. glandulifera in forest habitats has accelerated, and could be facilitated by (1) the strong pressure of propagules from widely spread riparian populations, (2) major disturbances, anthropogenic or natural, of forest ecosystems, (3) the increased use of forestry machinery capable of transporting seeds and (4) the high environmental tolerance of the species. The impacts of I. glandulifera in forest habitats can include negative impacts on the diversity of native plants and mycorrhizal fungi. I. glandulifera can also have a negative impact on the growth of planted forest plants. Measures listed to prevent the spread of I. glandulifera towards the forests: limitation of the disturbances of the ground and the transport of soil contaminated by seeds, logging before the release of the seeds of I. glandulifera in order to minimize any further spread (Čuda et al. 2020).

Management

Action plan

An action plan concerning the Himalayan Balsam has been published in 2020:

→ Finalised Action Plan for Impatiens glandulifera (Pfeiffenschneider & Hoppe 2020)

Valley of the Syr (Gutland)

In 2016, the federation of municipalities SIAS launched an eradication campaign along the river Syr. The shores of the Syr and its tributaries are partially covered with Himalayan Balsam. Since 2016, the affected parts of the water have been inspected annually and the plants removed if necessary in order to stem the further spread of the plants. In 2018, neophytes were removed over a length of approximately 3.9 km, where around 1.5 km between Moutfort and Oetrange was more severely infested, the 2.4 km from Oetrange towards Schuttrange less so. The annual removal of the balsam seems to improve the water sections (Anonymous 2014b: 4; “Aktionsplan Neophyten” in Anonymous 2019: 4).

Valley of the Blees (Oesling)

On 4 July 2009, the Nature Park Our took his first steps in the management of Impatiens glandulifera on the river Blees under the coordination of Béatrice Casagranda, involving a dozen volunteers, amongst others staff from Foundation “Hëllef fir d’Natur”. At the time, this action was strongly criticized by several beekeepers.

In summer 2017 the Nature Park of the Our Valley launched a pilot project to free the small river Blees (20 km) from Himalayan Balsam, in co-operation with the National Museum of Natural History (Ehl & Gengler 2018; Ehl 2019). At the beginning, the project focused on the first 4 km of the river Blees, in order to avoid new upstream invasions. Several habitats along the river were heavily impacted by the presence of Himalayan Balsam. In the starting year of the project, the management was exclusively done manually, which turned out to be not efficient enough for most impacted zones. The collected biomass is transported for treatment to the biogas plant in Hosingen (Klein 2019).

In 2018, the management was significantly improved through the use of brushcutters beside the manual management in less accessible zones. This led to a significantly lower presence of individuals at the beginning of the 2019 management season. Thus, the management workload could be reduced by half, which allowed extension of the management by an extra 2 km downstream. We expect more tangible results in the years to come (Klein 2019).

In the course of 2019, the successes achieved so far in the control of Himalayan balsam on the Blees from the previous year have been confirmed. In addition to a large-scale reduction in linear stands, fewer punctual stands were also detected. It also became apparent that the control of dense stands, which were not very successfully collected by hand in 2017, can lead to lasting success with mechanical measures. For example, after the large-scale expansion in July 2018, the populations in the ‘Iwwer Ehlerhämicht’ area had already declined significantly or even disappeared completely by October after the first mechanical work; even in 2019, only small residual populations were found in this area. However, manual collection, which is a less invasive control method, was successful in the less densely overgrown areas and should continue to be used in such low-density stands or as a follow-up measure after multi-annual mowing (Ehl 2020).

Despite the declines in population observed so far, it is urgently not advisable to stop the systematic control of Himalayan balsam in the northern study area in the upper reaches of the Blees. As described in the literature and confirmed in our observations, incomplete control (even with 99% population decline) is almost as ineffective as if no measures had been implemented at all (Wadsworth et al. 2002). In the Stommert and Ënner Fuusselach areas, larger populations have developed again in 2019 from the existing seed bank or from individual plants remaining in the control areas. Successful control is therefore only possible if every single plant of the Himalayan balsam is removed during control so that the existing seed bank cannot renew itself. In addition to the recommended combination of mechanical work in the case of extensive stands and manual collection in the case of smaller stands or in the case of follow-up maintenance, the work must be carried out systematically over a longer period of time (Ehl 2020, Ehl at al 2023).

Nature park Mullerthal (Gutland)

On July 27, 2019, a management action against Himalayan Balsam took place around the Consdorf Mill and the upstream ponds. About ten people participated in the action, which also raised awareness among people walking on the trails adjacent to the managed sites. The green waste generated by the action was evacuated to the Miny biogas facility in Nommern. A problem with the removed biomass was the relatively large volume of soil attached to the roots. In order to avoid this problem in the future, it is recommended to leave the roots on the site (Pfeiffenschneider 2019: 1).

Neighbouring countries

Successful management of Himalayan Balsam has been reported from two regions in France: the catchment areas of the river Risle (Eure) (Royer & Blottière 2019) and the river Graine (Haute-Vienne et Charente) (Fernandez 2015).

Risk assessment

ISEIA protocol

A3 (3+3+2+3) = Black List (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,52 = (Overall Invasion score 0,87 x Overall Impact score 0,60) (Ries et al. 2020).

Worldwide distribution

Alien Impatiens taxa

Six alien balsam species have been reported in Luxembourg, Impatiens noli-tangere L. being the only native species.

• Impatiens balfourii Hook.f.: Balfour’s touch-me-not, first observed in 2016 in the wild in Luxembourg.
• Impatiens balsamina L.: the garden balsam is already mentioned in Krombach’s flora of 1875 as “Introduced from the East Indies and grown in all gardens” (Krombach 1875: 56).
• Impatiens capensis Meerb. is an annual plant native to eastern North America that is currently spreading across Europe. In Luxembourg, it was first reported on 2021-10-11 from the Moselle valley.
• Impatiens glandulifera Royle: the invasive Himalayan Balsam, which is widespread in riparian ecosystems and forests across Luxembourg.
• Impatiens parviflora DC.: the small balsam, which is widespread in forests across Luxembourg.
• Impatiens walleriana Hopok. f. was reported once as cultivated in Rumelange in 1946.

In 2011 the annual hybrid Impatiens parviflora × I. balfourii was discovered in the canton of Ticino in Switzerland. The fertile hybrid with alternating leaves can be up to 60 cm high. Considerable populations of the hybrid were observed in 2014 in the canton of Ticino in the absence of the parent species (Van Valkenburg et al. 2019).

Fact sheet and leaflet

PDF fact sheet of the Nature and Forestry Administration: FR | DE

In early spring 2020 the Department for the Environment of the Luxembourg Ministry for environment, climate and sustainable development edited leaflets in German and French about Fallopia japonica, in co-operation with the National Museum of Natural History and efor-ersa ingénieurs-conseils. They can be downloaded here in PDF format (~ 4 MB each).

 

Bibliography

• Albers, M., S. Kohn, J. Steng & M. Pfeiffenschneider, 2001. – Problematik der Bioinvasion. Kartierung von Japan-Knöterich, Riesenbärenklau und Indischem Springkraut an Woltz, Clerve und Wiltz. Ergebnisse der Kartierung. – Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, arrondissement nord. August 2001. 7S. + Anhang.
• Anonymous, 2014. Regulation (EU) No 1143/2014 of the European Parliament and of the Council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species. Official Journal of the European Union L 317: 35-55 (4.11.2014).
• Anonymous, 2014. Naturschutz in den SIAS-Gemeinden 2014. La sauvegarde du patrimoine naturel dans les communes du SIAS. n.p. Biologische Station – Naturzenter SIAS. URL: http://www.sias.lu/dl/Infoblad_2014_1404503.pdf [accessed 2019-10-11]
• Anonymous, 2017. Commission implementing regulation (EU) 2017/1263 of 12 July 2017 updating the list of invasive alien species of Union concern established by Implementing Regulation (EU) 2016/1141 pursuant to Regulation (EU) No 1143/2014 of the European Parliament and of the Council. Official Journal of the European Union L 182: 37-39 (13.7.2017).
• Anonymous, 2019. Tätigkeitsbericht 2018. Biologische Station SIAS. URL: http://www.sias.lu/dl/Taetigkeitsbericht2018.pdf [accessed 2019-10-11]
• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum, F. Verloove & A. Vervoort, 2010. Harmonia database: Impatiens glandulifera Royle. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-09]
• CABI, 2021. Impatiens glandulifera. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2021-03-04]
• Čuda J., H. Skálova & P. Pyšek, 2020. Spread of Impatiens glandulifera from riparian habitats to forests and its associated impacts: insights from a new invasion. Weed Research 60: 8-15.
• Ehl, S. & C. Gengler, 2018. Pilotprojekt zur systematischen Bekämpfung von Impatiens glandulifera an der Blees [Bericht 2017]. Projektbericht, EFOR-ERSA, 21 S. + Anhang.
• Ehl, S., 2019. Bekämpfung von Impatiens glandulifera an der Blees – Bericht 2018. Projektbericht, EFOR-ERSA, 25 S. + Anhang.
• Ehl, S., 2020. Bekämpfung vom Impatiens glandulifera an der Blees – Bericht 2019. Projektbericht, EFOR-ERSA, 37 S. + Anhang.
• Ehl, S., A. Klein & C. Ries, 2023. It’ s a marathon, not a sprint: The management of Impatiens glandulifera at the upper reaches of the river Blees in the Naturpark Our (Luxembourg). Bulletin de la Société des naturalistes luxembourgeois 125: 25-36.
• Fernandez, S., 2015. Interventions de gestion de la Balsamine de l’Himalaya sur le bassin versant de la Graine. URL: http://www.especes-exotiques-envahissantes.fr/wp-content/uploads/2018/10/balsamine_r.pdf [accessed 2019-10-22]
• Glesener, B., M. Pfeiffenschneider & C. Ries, 2009. Die Verbreitung von Impatiens glandulifera, Fallopia japonica, F. sachalinensis, F. ×bohemica und Heracleum mantegazzianum entlang der Hauptfließgewässer Luxemburgs. Bull. Soc. Nat. luxemb. 110 : 69-73. (pdf)
• Kariger, J.-J., 1961. Plantes intéressantes, rares ou nouvelles pour le Grand-Duché de Luxem­bourg, trouvées en 1957 et 1958. Bull. Soc. Nat. luxemb. 63: 100-103.
• Klein, A., 2019. Personal communication giving a résumé of the project by email to C. Ries on 18 October 2019.
• Klein, E.J., 1897. Die Flora der Heimat : Sowie die hauptsächlichster bei uns kultivierten fremden Pflanzenarten biologisch betrachtet : Eine Anleitung zur selbständigen Beobachtung der Lebens- und Anpassungserscheinungen in der Pflanzenwelt. Diekirch: J. Schroell., 552 pp.
• Krippel, Y., T. Helminger & G. Colling, 2020. Notes floristiques. Observations faites au Luxembourg (2018-2019). Bulletin Soc. Nat. luxemb. 122 : 29-55. [PDF 132 KB]
• Krippel, Y. & R. Proess, 2017. Impatiens balfourii Hook. f. (Balsaminaceae), nouvelle espèce subspontanée au Luxembourg ?. Bull. Soc. Nat. luxemb. 119: 55-61.
• Krombach, J.-H.-G., 1875. Flore du grand-duché de Luxembourg. Plantes phanérogames. 564 p. Luxembourg, Imprimerie Joris.
• Lambinon J. & F. Verloove, 2012. Nouvelle flore de la Belgique, du grand-duché de Luxembourg, du Nord de la France et des régions voisines. Sixième édition. Avec la collaboration de L. Delvosalle, B. Toussaint, D. Geerinck, I. Hoste, F. Van Rossum, B. Cornier, R. Schumacker, A. Vanderpoorten et H. Vannerom. Jardin botanique national de Belgique, Meise. CXXXIX + 1195 pp. ISBN : 9789072619884.
• MNHNL, 2000-. Impatiens glandulifera Royle in Recorder-Lux, database on the natural heritage of the Grand Duchy of Luxembourg. Musée national d’histoire naturelle, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-10-09]
• MNHNL, iNaturalist & GBIF, 2019. Impatiens glandulifera Royle in MNHNL-mdata, online portal combining species observation from Recorder-Lux, iNaturalist and GBIF. National Museum of Natural History, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-10-09]
• Pfeiffenschneider, M., 2001. – Problematik der Bioinvasion. Nationales Inventar von Riesenbärenklau, Indischem Springkraut und exotischen Knötericharten. Ergebnisse einer Umfrage und Konzept zur Bekämpfung der Riesenbärenklaubestände. – Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, Service de la conservation de la nature, November 2001. 23 S. + Anhang, Luxembourg.
• Pfeiffenschneider, M., 2007. Über die Verbreitung von Heracleum mantegazzianum, Impatiens glandulifera, Fallopia japonica und F. sachali­nensis entlang der Gewässer Obersauer, Woltz, Clerve, Wiltz und ihrer Nebengewässer (Luxemburg). Bull. Soc. Nat. luxemb. 108 : 7-10. (pdf)
• Pfeiffenschneider, M., 2008. Neophyten in Luxemburg – Projekt Bioinvasion 2007. Arbeitsbericht. 18 S. (pdf)
• Pfeiffenschneider, M., 2019. Plan d’action pour la lutte contre les principales plantes exotiques envahissantes dans les parcs naturels de l’Our et du Mullerthal. Procès verbal de la réunion du 24 septembre 2019. 3p.
• Pfeiffenschneider, M. & F. Hoppe 2020. Plan d’action pour espèces exotiques envahissantes au Grand-Duché de Luxembourg : Impatiente de l’Inde, Impatiens glandulifera (Royle). Version du 2020-06-15. Administration de la nature et des forêts, Luxembourg. 19 pp.
• Pfeiffenschneider, M. & M. Owaller, 2000. – Kartierung von Japan-Knöterich, Riesenbärenklau und Indischem Springkraut an der Obersauer. Theoretische Grundlagen und Ergebnisse der Kartierung.. – Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, acrrondissement nord. August 2000. 37S. + Anhang, Luxembourg.
• Pfeiffenschneider, M., P. Gräser & C. Ries, 2014. Distribution of selected neophytes along the main rivers of Luxembourg. Bull. Soc. Nat. luxemb. 115: 101-108. [PDF 3668 KB]
• Ries, C. & Y. Krippel, 2021. First records of 56 invasive alien vascular plants in Luxembourg. Bulletin de la Société des naturalistes luxembourgeois 123: 115-127. [PDF 241 KB]
• Ries, C., Y. Krippel & M. Pfeiffenschneider, 2020. Risk assessment after the Harmonia+ protocol of invasive alien vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 122: 197-205. [PDF 132 KB]
• Ries, C., Y. Krippel, M. Pfeiffenschneider & S. Schneider, 2013. Environmental impact assessment and black, watch and alert list classification after the ISEIA Protocol of non-native vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 114: 15-21. [PDF 652 KB]
• Royer, R. & D Blottière, 2019. Éradication de la Balsamine de l’Himalaya par arrachage manuel sur plusieurs sites de la Risle (Eure). URL: http://especes-exotiques-envahissantes.fr/wp-content/uploads/2019/10/rex_balsamine-eure_vf.pdf [accessed 2019-10-22]
• Wadsworth, R.A., Collingham, Y.C., Willis, S.G., Huntley, B. & Hulme, P.E. (2002): Simulating the spread and management of alien riparian weeds: are they out of control? British Ecological Society. Journal of Applied Ecology 37: 28-38.

 Page content last updated on 2024-07-31. Last proofread by Caroline Grounds on 2019-11-19.

1. Cf. CABI 2021.[↩]

	Giant hogweed	Status LU: established. 1st record: LU ~1934, ITW 1980.
	Rise-Biereklo	Status Eur.: established. 1st record: UK 1817. IAS of EU concern (2017).
	Berce du Caucase, berce de Mantegazzi	RA: ISEIA: A3, Black List. Harmonia+: 0,64.
	Riesen-Bärenklau, Herkulesstaude	Wikipedia: | Wikispecies: | CABI
	Reuzenberenklauw, Perzische berenklauw	Back to the list of neophytes

Brief description

Heracleum mantegazzianum Somm. et Lev. inhabits moist and nutrient-rich soils in ruderal places, along roadsides, riverbanks and forest margins, in abandoned or neglected grasslands and in tall-herb communities. It is poorly represented in old successional stages but can occur in open alluvial forests. It usually invades sites with a low management intensity. Seeds are usually dispersed in the vicinity of mother plants except when growing near rivers. In that case, they may be transported over several kilometres.

The enormous height and leaf area of the giant hogweed enable it to overtop most indigenous herbaceous plant species typical of early stages of natural successions. It may form dense populations that absorb up to 80% of the incoming light and out-compete most light-demanding species. However, its abundance decreases in old successional stages due to competition with trees. Besides the ecological problems, tall invasive hogweed species also represent a serious health hazard for humans. The plant exudes a clear watery sap, which contains several photosensitising furanocoumarins. Upon contact with human skin and in combination with ultraviolet radiation, these compounds cause severe burning of the skin (Branquart et al. 2010).

IAS of Union concern

In 2017, Heracleum mantegazzianum Somm. et Lev. was added to the list of invasive alien species of Union concern (Anonymous 2017) which implies that member states shall take all necessary steps to prevent it’s unintentional introduction or spread.

Status and distribution in Luxembourg

The melliferous plant Heracleum mantegazzianum Somm. et Lev. was introduced to Luxembourg by the Luxembourg botanist Edmond Joseph Klein (1866-1942) in the 1930s. In 1935, a flowering giant hogweed made his front garden in avenue Grande-Duchesse-Charlotte in Luxembourg City an attraction for naturalists and beekeepers, who collected seeds to grow the plant in their gardens or near their beehives (Reichling 2008). This explains why many large populations of this plant in Luxembourg are a result of plantation by beekeepers. As the species is perennial and needs at least one year to develop before flowering, we can assume that Klein introduced seeds of the species to Luxembourg before 1934 and sowed them in or before 1934, which we consider the first record of the species in Luxembourg.

The south-west Asian species was first documented in 1980 near Garnich by Léopold Reichling (1921-2009): “A colony of about a hundred feet is known to be located N of the Luxembourg-Arlon railway line east of the Garnich-Windhof road. Recent road works have reduced its importance.” (Reichling 1990: 62; MNHNL 2000-). Cultivated for ornamental use in parks and gardens. Subspontaneous or naturalized, quite rare, mostly widespread in urban areas and along highways; often abundant in its stations. Introduced in Brussels in the 1930s, this species has experienced, especially since the 1980s, a strong expansion in the Flora territory, as in other regions of Europe (Lambinon & Verloove 2012: 524).

Giant hogweed was getting very common and widespread in Luxembourg during the period 2000-2010. It generally occurred in small clusters along river banks, several major rivers of Luxembourg having been affected. Sometimes the species formed dense stands along rivers, bicycle ways and rail roads or on waste land. Since 2008 many stakeholders are involved in control measures resulting in the decline of the species. This might result in the downgrade of the ISEIA-code of the species (A3) in future risk assessments.

End of 2023, 560 records of this melliferous species were listed in the MNHNL-mdata online portal (MNHNL, iNaturalist & GBIF 2019). As is the case for many species, the shown map doesn’t reflect the actual status of the species, but its historical distribution accumulated in time.

Hybrids and other taxa

It is known that Heracleum mantegazzianum can hybridise with H. sphondylium (Heracleum mantegazzianum Somm. and Lev. × H. sphondylium L. var. dissectum Le Gall).

In Luxembourg, the hybrid has so far been detected 3 times in the north of the country: Harlange in 2014 (Krippel & Colling 2016: 37), Kuborn in 2016 (Krippel et al. 2018: 64), and Nothum in 2018 (Krippel et al. 2020: 39).

Other taxa that are more or less neighbouring are also sometimes cultivated for ornamental purposes. Thus, the subspontaneous state of Heracleum laciniatum Hornem. (Syn. Heracleum giganteum Hort.) has been reported in the territory of the Flora, but it has been hypothesized that they would actually be hybrids of Heracleum mantegazzianum × sphondylium. The taxonomy of large Asian Heracleum species introduced into Europe should be re-examined (Lambinon & Verloove 2012: 524).

Management

Since 2008, the Luxembourg Water Management Authority is systematically controlling giant hogweed on the river banks of the major rivers of Luxembourg and is running special units for this purpose.

The Upper-Sûre Nature Park in the north-west of Luxembourg (Ardennes) runs a monitoring and management plan on giant hogweed since 2009 in the frame of the national action plan “Heracleum mantegazzianum” (Krippel & Richarz 2013). The inventories show a prevalence of H. mantegazzianum populations in two valleys i.e. Harelerbaach and Dirbech, where the plants are growing predominately on riversides and alluvial meadows. Since 2009, the management plan is annually reviewed and consequently executed in the Upper-Sûre region. Giant hogweed is controlled by root cutting and, in the case of flowering plants, by umbel removal. These simple mechanical methods give excellent results, but have to be continued for several years, until the soil seed bank is depleted, especially in the valleys of the Surbich and Harelerbaach (Krippel & Colling 2014, 2016; Krippel et al. 2018: 64). At Tutschemillen, this invasive exotic species remains despite its regular elimination by the services of the Haute-Sûre Nature Park (Krippel et al. 2020: 39).

Since 2009, after a sensitisation campaign by the Nature and Forest Agency, several foresters systematically control giant hogweed in their areas.

Since 2010, the city of Luxembourg systematically controls hogweed on its grounds, especially along the Alzette river.

In 2012, three workers of the national railway company CFL were burned by giant hogweed while cleaning up an overgrown area of a railway station. A survey of several neophyte species on the national railway network (Pfeiffenschneider et al. 2014d) resulted in four sites identified with Heracleum, which were subsequently controlled in the same year.

Action plan

An action plan regarding Giant Hogweed has been published in 2020:

→ Finalised Action Plan for Heracleum mantegazzianum (Pfeiffenschneider & Hoppe 2020)

Giant hogweed auger

In order to facilitate the control, an auger was developed by a Dutch company (https://www.eijkelkamp.com). The giant hogweed auger removes the roots of the giant hogweed ergonomically and effectively, preventing the plant from germinating again. For effective control, it is advisable to remove the roots from the non-flowering specimens both in the spring before flowering and in the autumn. The auger body is 33 cm long, with a diameter of 89 mm. The one-piece auger has a total length of 111.4 cm. The auger is easily emptied using a bent spatula.

Burn cases in Luxembourg

The Department of Ecology of the National Museum of Natural History made two surveys among physicians in Luxembourg on burns caused in 2008 and in 2011 and 2012 (cf. Ries et al. 2013). Results showed that there have been at least 60 cases of burns in 2011 and 2012, while the previous survey back in 2008 resulted in no feedback on burn cases. These features are in line with the ongoing spread of the species in that period in Luxembourg. Most victims were aged between 18 and 60 and have been affected by burns in summer. The severity of burns ranged from not severe to medium.

Special observations:

• When controlling giant hogweed during full flowering, the dust generated during removal of the flowers can penetrate between the protective clothing and the throat of a worker and cause a line or strip of burned skin (Adm. de la gestion de l’eau, personal communication, 2013).
• In 2013, children suffered burns when playing with the previous year’s withered stems in early spring (Danièle Dammé, personal communication, May 20, 2014).

Useful documents

• National sensitisation campaign in Luxembourg in 2014:
  – Flyer in French and German [pdf 1,7 MB]
  – Poster in French and German [pdf 1 MB]
• Basic information poster about giant hogweed (English, Deutsch, Français, Nederlands) [jpg 3,5 MB]
• The giant hogweed Best Practice Manual (English, Deutsch, Français) [pdf 2,5 MB]

Risk assessment

ISEIA protocol

A3 (3+3+2+3) = Black List (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,64 = (Overall Invasion score 0,77 x Overall Impact score 0,83) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Albers, M., S. Kohn, J. Steng & M. Pfeiffenschneider, 2001. Problematik der Bioinvasion. Kartierung von Japan-Knöterich, Riesenbärenklau und Indischem Springkraut an Woltz, Clerve und Wiltz. Ergebnisse der Kartierung. Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, arrondissement nord. August 2001. 7S. + Anhang.
• Anonymous, 2017. Commission implementing regulation (EU) 2017/1263 of 12 July 2017 updating the list of invasive alien species of Union concern established by Implementing Regulation (EU) 2016/1141 pursuant to Regulation (EU) No 1143/2014 of the European Parliament and of the Council. Official Journal of the European Union L 182: 37-39 (13.7.2017).
• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum, F. Verloove & A. Vervoort, 2010. Harmonia database: Heracleum mantegazzianum Somm. et Lev.. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-11]
• CABI, 2019. Heracleum mantegazzianum. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2020-03-02]
• Glesener, B., M. Pfeiffenschneider & C. Ries, 2009. Die Verbreitung von Impatiens glandulifera, Fallopia japonica, F. sachalinensis, F. ×bohemica und Heracleum mantegazzianum entlang der Hauptfließgewässer Luxemburgs. Bull. Soc. Nat. luxemb. 110 : 69-73. (pdf)
• Krippel, Y. & F. Richarz, 2013. Verbreitung und Management von Heracleum mantegazzianum Somm. et Lev. (Apiaceae, Spermatophyta) in der Obersauerregion in Luxemburg. Bull. Soc. Nat. luxemb. 114: 3-13. (pdf)
• Krippel, Y. & G. Colling, 2014. Notes floristiques. Observations faites au Luxembourg (2012-2013). Bull. Soc. Nat. luxemb. 115: 109-124.
• Krippel, Y. & G. Colling, 2016. Notes floristiques. Observations faites au Luxembourg (2014-2015). Bull. Soc. Nat. luxemb. 118: 27-51. [PDF 1.33 MB]
• Krippel, Y., T. Helminger & G. Colling, 2018. Notes floristiques. Observations faites au Luxembourg (2016-2017). Bull. Soc. Nat. luxemb. 120: 57-76. [PDF 265 KB]
• Krippel, Y., T. Helminger & G. Colling, 2020. Notes floristiques. Observations faites au Luxembourg (2018-2019). Bulletin Soc. Nat. luxemb. 122 : 29-55. [PDF 132 KB]
• Lambinon J. & F. Verloove, 2012. Nouvelle flore de la Belgique, du grand-duché de Luxembourg, du Nord de la France et des régions voisines. Sixième édition. Avec la collaboration de L. Delvosalle, B. Toussaint, D. Geerinck, I. Hoste, F. Van Rossum, B. Cornier, R. Schumacker, A. Vanderpoorten et H. Vannerom. Jardin botanique national de Belgique, Meise. CXXXIX + 1195 pp. ISBN : 9789072619884.
• MNHNL, 2000-. Heracleum mantegazzianum Somm. et Lev. in Recorder-Lux, database on the natural heritage of the Grand Duchy of Luxembourg. Musée national d’histoire naturelle, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-10-11]
• MNHNL, iNaturalist & GBIF, 2019. Heracleum mantegazzianum Somm. et Lev. in MNHNL-mdata, online portal combining species observation from Recorder-Lux, iNaturalist and GBIF. National Museum of Natural History, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-10-11]
• Pfeiffenschneider, M., 2001. Problematik der Bioinvasion. Nationales Inventar von Riesenbärenklau, Indischem Springkraut und exotischen Knötericharten. Ergebnisse einer Umfrage und Konzept zur Bekämpfung der Riesenbärenklaubestände. Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, Service de la conservation de la nature, November 2001. 23 S. + Anhang, Luxembourg.
• Pfeiffenschneider, M., 2007. Über die Verbreitung von Heracleum mantegazzianum, Impatiens glandulifera, Fallopia japonica und F. sachali­nensis entlang der Gewässer Obersauer, Woltz, Clerve, Wiltz und ihrer Nebengewässer (Luxemburg). Bull. Soc. Nat. luxemb. 108 : 7-10. (pdf)
• Pfeiffenschneider, M., 2008. Neophyten in Luxemburg – Projekt Bioinvasion 2007. Arbeitsbericht. 18 S. (pdf)
• Pfeiffenschneider, M. & F. Hoppe, 2020. Plan d’action pour espèces exotiques envahissantes au Grand-Duché de Luxembourg : Berce géante, Heracleum mantegazzianum Sommier & Levier 1895. Version du 2020-09-23. Administration de la nature et des forêts, Luxembourg. 20 pp
• Pfeiffenschneider, M., P. Gräser & C. Ries, 2014a. Distribution of selected neophytes along the main rivers of Luxembourg. Poster in 2 parts at XXXIe réunion annuelle des collaborateurs scientifiques du Musée national d’histoire naturelle Luxembourg, 15.03.2014. (pdf 2,7 MB)
• Pfeiffenschneider, M., P. Gräser & C. Ries, 2014b. Distribution of selected neophytes along the national railway network of Luxembourg. Poster at XXXIe réunion annuelle des collaborateurs scientifiques du Musée national d’histoire naturelle Luxembourg, 15.03.2014. (pdf 1,4 MB)
• Pfeiffenschneider, M., P. Gräser & C. Ries, 2014c. Distribution of selected neophytes along the main rivers of Luxembourg. Bull. Soc. Nat. luxemb. 115: 101-108. [PDF 3668 KB]
• Pfeiffenschneider, M., P. Gräser & C. Ries, 2014d. Distribution of selected neophytes along the national railway network of Luxembourg. Bull. Soc. Nat. luxemb. 115: 95-100. [PDF 1457 KB]
• Pfeiffenschneider, M. & M. Owaller, 2000. Kartierung von Japan-Knöterich, Riesenbärenklau und Indischem Springkraut an der Obersauer. Theoretische Grundlagen und Ergebnisse der Kartierung. Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, acrrondissement nord. August 2000. 37S. + Anhang, Luxembourg.
• Reichling, L., 1990. Observations floristiques au Luxembourg 1980-1989. Bulletin de la Société des naturalistes luxembourgeois 90: 55-70. [PDF 808 KB]
• Reichling, L., 2008. Personal communication to C. Ries.
• Ries, C. & Y. Krippel, 2021. First records of 56 invasive alien vascular plants in Luxembourg. Bulletin de la Société des naturalistes luxembourgeois 123: 115-127. [PDF 241 KB]
• Ries, C., Y. Krippel, M. Pfeiffenschneider & S. Schneider, 2013. Environmental impact assessment and black, watch and alert list classification after the ISEIA Protocol of non-native vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 114: 15-21. [PDF 652 KB]
• Ries, C., Y. Krippel & M. Pfeiffenschneider, 2020. Risk assessment after the Harmonia+ protocol of invasive alien vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 122: 197-205. [PDF 132 KB]
• Ries, C, Y. Steil & M. Pfeiffenschneider, 2013. Survey amongst physicians in Luxembourg on burns caused in 2011 and 2012 by the giant hogweed (Heracleum mantegazzianum SOMMIER & LEVIER, Apiaceae). Poster at XXXe réunion annuelle des collaborateurs scientifiques du Musée national d’histoire naturelle Luxembourg, 16.03.2013. (pdf 1,2 MB)

 Page content last updated on 2024-07-31. Last proofread by Caroline Grounds on 2019-11-11.

	Japanese Knotweed	Status LU: established. 1st record: LU 1849, ITW <1872.
	Japanescht Knuetkraut	Status Eur.: established. 1st record: NL 1847.
	Renouée du Japon, renouée bambou	RA: ISEIA: A3 – Black List. Harmonia+: 0,63
	Japanischer Staudenknöterich, J. Flügelknöterich	Wikipedia:   | Wikispecies: | CABI
	Japanse duizendknoop	Back to the list of neophytes

Brief description

Like other Asiatic knotweeds, Japanese knotweed colonises a wide range of environments, with a predilection for moist and nitrogen-rich soils. It prefers sunny places or semi-shaded habitats. This pioneer plant proliferates both in ruderal and semi-natural habitats, including riparian areas and open forests. It doesn’t produce any seed and reproduces clonally. Stem and rhizomes may easily split into small pieces; fragments are able to regenerate a plant, provided a node is present. Transport of garden waste and soil contaminated with rhizomes are the major dispersal modes. Where the plant is widely consolidated on river banks it is also spread by floods and can easily colonise downstream (Branquart et al. 2010).

Fallopia japonica is able to monopolise space and to form dense and persistent populations. It can outcompete most native herbaceous plant species thanks to early seasonal development, high growth rate and productivity, abundant leaf cover, allelochemical production and clonal spread associated with an extraordinarily high rate of proliferation of below-ground organs. It also decreases soil bulk density and pH, increases organic matter content and enhances nutrient cycling rates, probably due to nutrient uplift. Its development reduces plant and invertebrate species diversity, alters habitats for fish and wildlife, changes light and energy conditions of the ecosystem, and favours river bank erosion during the winter. Prolific rhizome and shoot growth can damage foundations, walls, pavements, and drainage works, and causes flood hazards by increasing resistance to water flow and damaging flood prevention structures (Branquart et al. 2010).

Uncertain status of Fallopia japonica in Luxembourg

Identification of knotweed species is not always easy, especially the very similar Japanese knotweed (Fallopia japonica) and Bohemian knotweed (Fallopia × bohemica), a hybrid between Japanese knotweed and Sakhalin knotweed (Fallopia sachalinensis). Until recently, Japanese knotweed was considered much more widespread in Luxembourg than Bohemian knotweed. During the field trip of the Neobiota 2016 conference in September 2016, knotweed populations near Michelau that were so far considered as F. japonica were identified by specialists as F. × bohemica.

To assess the accuracy of the data collected to date, the Department of Ecology of the Museum carried out a small survey in 2017:  31 specimens of knotweed populations were collected across the country, described and filed in the museum’s herbarium. Genetic analysis of the samples in the museum’s lab showed that in Luxembourg F. × bohemica is more common than Fallopia japonica. The data of both taxa need to be updated in the Recorder-Lux database (MNHNL, 2000-).

Status and distribution in Luxembourg

Koltz (1875: 127) reports that Fallopia japonica (Houtt.) Ronse Decr. (under its synonym Polygonum cuspidatum Sieb. & Zucc.) was introduced in 1849 in Luxembourg by Philipp Franz von Siebold (1796–1866)¹ in the park of the Royal residence (castle) in Walferdange, two years after Siebold introduced the species from Japan² to The Netherlands (Bailey & Conolly 2000: 94), and one year before the species was sent to the Royal Botanical Gardens at Kew, UK, in 1850 (Bailey & Conolly 2000: 97, CABI 2021).

This is inline with Eugène Fischer (1821-1903), who reports that Fallopia japonica (Houtt.) Ronse Decr. was introduced in Luxembourg about 20 years before 1872 (Fischer 1872: 89). He lists the species under its synonym Polygonum cuspidatum Sieb.³ Some twenty years after its introduction, Fischer already had a feeling of the potential of this species as an invasive species: “Siebold’s knotweed […], originating from Japan, was introduced as ornamental crops in the Grand Duchy around 1852. It is very tractable, remarkable for its great development and its great rusticity, which allows it to grow in all terrain and at all exposures. It multiplies and is maintained with such ease that it returns without culture and care to some gardens and nearby. I am inclined to believe that it will now remain in the country as a subspontaneous plant.”⁴

Around 1873-1875, Japanese knotweed (Polygonum cuspidatum) was quite common in Luxembourg, cultivated in gardens and appeared sometimes subspontaneously in their vicinity (Koltz 1873: 142; Krombach 1875: 379).

The first herbarium specimen of the species in Luxembourg dates from 1947. On 11th July 1947, François Léon Lefort (1917-1975) collected a specimen near the Carmel in Luxembourg City (Specimen № 22229, MNHNL 2000-).

According to Lambinon & Verloove (2012: 193), the species occurs on wasteland, embankments, stream banks, forest edges. Sometimes grown for ornamental purposes in parks (formerly also as fodder). Fairly common to fairly rare (AC-AR) and naturalised in all flora districts, very invasive.

Currently, 1140 records of the species and its subspecies are accessible through the MNHNL-mdata portal (MNHNL, iNaturalist & GBIF 2019). As outlined in the section above, these data have to be revised, as most of these records could have been misidentified, which is why we describe both taxa together in the following section.

Importance and distribution of Japanese and Bohemian knotweed in Luxembourg

Bohemian and Japanese knotweed are common and widespread invasive neophytes in Luxembourg. They build huge colonies along riparian ecosystems, several major rivers of Luxembourg being affected. They regularly grow in small patches along roadsides and in waste grounds, most of these places having been “contaminated” by people getting rid of knotweed clippings from their gardens. Examples can be seen along the main road leaving Luxembourg City in the direction of Echternach. Nurseries and garden designers sometimes contribute to the spread of knotweed in gardens and public green spaces by using contaminated compost.

Risk assessment

ISEIA protocol

A3 (3+3+3+3) = Black List (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,63 = (Overall Invasion score 0,84 x Overall Impact score 0,75) (Ries et al. 2020).

Worldwide distribution

Leaflet

In early spring 2020 the Department for the Environment of the Luxembourg Ministry for environment, climate and sustainable development edited leaflets in German and French about Fallopia japonica, in co-operation with the National Museum of Natural History and efor-ersa ingénieurs-conseils. They can be downloaded here in PDF format (~ 4 MB each).

  

Bibliography

• Albers, M., S. Kohn, J. Steng & M. Pfeiffenschneider, 2001. – Problematik der Bioinvasion. Kartierung von Japan-Knöterich, Riesenbärenklau und Indischem Springkraut an Woltz, Clerve und Wiltz. Ergebnisse der Kartierung. – Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, arrondissement nord. August 2001. 7S. + Anhang.
• Bailey, J.P. & A.P. Conolly, 2000. Prize-winners to pariahs – A history of Japanese Knotweed s.l. (Polygonaceae) in the British Isles. Watsonia. 23: 93–110.[PDF]
• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum, F. Verloove & A. Vervoort, 2010. Harmonia database: Fallopia japonica (Houtt.) Ronse Decr. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-09]
• CABI, 2021. Fallopia japonica. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2021-03-04]
• Fischer, E., 1872. Les plantes subspontanées et naturalisées de la flore du grand-duché de Luxembourg. Publications de l’Institut royal grand-ducal de Luxembourg, section des sciences naturelles et mathématiques XII: 1-115. Imprimerie V. Buck, Luxembourg.
• Glesener, B., M. Pfeiffenschneider & C. Ries, 2009. Die Verbreitung von Impatiens glandulifera, Fallopia japonica, F. sachalinensis, F. ×bohemica und Heracleum mantegazzianum entlang der Hauptfließgewässer Luxemburgs. Bull. Soc. Nat. luxemb. 110 : 69-73. (pdf)
• Krombach, J.-H.-G., 1875. Flore du grand-duché de Luxembourg. Plantes phanérogames. 564 p. Luxembourg, Imprimerie Joris.
• Lambinon J. & F. Verloove, 2012. Nouvelle flore de la Belgique, du grand-duché de Luxembourg, du Nord de la France et des régions voisines. Sixième édition. Avec la collaboration de L. Delvosalle, B. Toussaint, D. Geerinck, I. Hoste, F. Van Rossum, B. Cornier, R. Schumacker, A. Vanderpoorten et H. Vannerom. Jardin botanique national de Belgique, Meise. CXXXIX + 1195 pp. ISBN : 9789072619884.
• MNHNL, 2000-. Fallopia japonica (Houtt.) Ronse Decr. in Recorder-Lux, database on the natural heritage of the Grand Duchy of Luxembourg. Musée national d’histoire naturelle, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-09-05]
• MNHNL, iNaturalist & GBIF, 2019. Fallopia japonica (Houtt.) Ronse Decr. in MNHNL-mdata, online portal combining species observation from Recorder-Lux, iNaturalist and GBIF. National Museum of Natural History, Luxembourg. URL: https://mdata.mnhn.lu [Accessed 2019-09-05]
• Pfeiffenschneider, M., 2001. – Problematik der Bioinvasion. Nationales Inventar von Riesenbärenklau, Indischem Springkraut und exotischen Knötericharten. Ergebnisse einer Umfrage und Konzept zur Bekämpfung der Riesenbärenklaubestände. – Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, Service de la conservation de la nature, November 2001. 23 S. + Anhang, Luxembourg.
• Pfeiffenschneider, M., 2007. Über die Verbreitung von Heracleum mantegazzianum, Impatiens glandulifera, Fallopia japonica und F. sachali­nensis entlang der Gewässer Obersauer, Woltz, Clerve, Wiltz und ihrer Nebengewässer (Luxemburg). Bull. Soc. Nat. luxemb. 108 : 7-10. (pdf)
• Pfeiffenschneider, M., 2008. Neophyten in Luxemburg – Projekt Bioinvasion 2007. Arbeitsbericht. 18 S. (pdf)
• Pfeiffenschneider, M. & M. Owaller, 2000. – Kartierung von Japan-Knöterich, Riesenbärenklau und Indischem Springkraut an der Obersauer. Theoretische Grundlagen und Ergebnisse der Kartierung.. – Studie des Büros ERSA im Auftrag von: Administration des eaux & forêts, acrrondissement nord. August 2000. 37S. + Anhang, Luxembourg.
• Ries, C. & Y. Krippel, 2021. First records of 56 invasive alien vascular plants in Luxembourg. Bulletin de la Société des naturalistes luxembourgeois 123: 115-127. [PDF 241 KB]
• Ries, C., Y. Krippel & M. Pfeiffenschneider, 2020. Risk assessment after the Harmonia+ protocol of invasive alien vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 122: 197-205. [PDF 132 KB]
• Ries, C., Y. Krippel, M. Pfeiffenschneider & S. Schneider, 2013. Environmental impact assessment and black, watch and alert list classification after the ISEIA Protocol of non-native vascular plant species in Luxembourg. Bull. Soc. Nat. luxemb. 114: 15-21. [PDF 652 KB]

 Page content last updated on 2023-02-27. Last proofread by Caroline Grounds on 2019-11-18.

1. In 1851 Philipp Franz von Siebold became an honorary member of the “Société naturelle dans le Grand-Duché de Luxembourg”, and in 1852 Commander of the Order of the Oak Crown [Ordre de la Couronne de chêne] (Luxembourg/Netherlands). [Source, PDF][↩]
2. Philipp Franz von Siebold was a German doctor who lived and worked for the Dutch on the Japanese island of Deshima[↩]
3. According to the Plants of the World online the correct/complete name of this synonym should be Polygonum cuspidatum Siebold & Zucc.[↩]
4. Original text: « La renouée de Siebold […], originaire du Japon, a été introduite dans les cultures ornementales du Grand-Duché vers 1852. Elle est très traçante, remarquable par son grand développement et sa grande rusticité qui lui permet de croître dans tous les terrains et à toutes les expositions. On la voit se multiplier et se maintenir avec tant de facilités qu’elle revient sans culture et sans soins dans quelques jardins et à proximité. Je suis porté à croire qu’elle se maintiendra dorénavant dans le pays comme plante subspontanée. » (Fischer 1872: 89)[↩]