Water fern	Status LU: established. 1st record: LU ~2002, ITW 2009.
	Waasserfar	Status Eur.: established. 1st record: 1870s-1880s.
	Fougère d’eau	RA: ISEIA: C1. Harmonia+: 0,22
	Großer Algenfarn	Wikipedia: | Wikispecies: | CABI
	Grote kroosvaren	Back to the list of neophytes

Brief description

Azolla filiculoides Lam. (Syn.: A. caroliniana Willd.) originates from tropical America and is naturalised in Western, South and Central Europe and the Canary Islands. Azolla filiculoides form stands that may expand or regress rapidly, depending in particular on thermal factors. Two species of Azolla have been reported in the Flora territory: A. filiculoides and A. caroliniana, but it is now known that these two names are synonymous (Lambinon & Verloove 2012: 41).

Azolla filiculoides is an aquatic fern that settles in ponds, ditches, water reservoirs, wetlands, channels and slow flowing rivers, often together with Lemna minuta. It does not tolerate turbulence or fast flowing water. The plant is spread by flood waters and by the movement of birds, animals and people. It can form dense, floating and monospecific mats at the surface of water bodies that reduce light penetration and gas exchange. These mats often reduce the development of algae, other aquatic plants and animals. However, dense populations seem to be transient and well localised (Branquart et al. 2010).

Status and distribution in Luxembourg

In Luxembourg, Azolla filiculoides was first reported around 2002 from a private garden pond by Claude Reckinger (in litt. 2021). The water fern was first observed in the wild by Karl-Georg Gessner on 10th July 2009 in three ponds close to Bourscheid (Kesselkapp), where it grew in more or less extended carpets in 3 ponds together with Lemna minor, Alisma plantagoaquatica and Glyceria fluitans (MNHNL 2000-, Krippel & Colling 2010: 12).

Discovered in several ponds located in the open countryside, this small fern native to tropical America was known for a few years already in Luxembourg in leisure ponds in private gardens, where it had been introduced with other aquatic plants (Krippel & Colling 2010: 12).

A spectacular proliferation of the water fern appeared in autumn 2005 in the channel of Jouy nearby Metz in French Lorraine (Muller 2006).

Risk assessment

ISEIA protocol

C1 (2+2+2+2) (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,22 = (Overall Invasion score 0,66 x Overall Impact score 0,33) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Branquart, E., I. Stiers, L. Triest, S. Vanderhoeven, W. Van Landuyt, F. Van Rossum, F. Verloove, 2010. Harmonia database: Azolla filiculoides Lam.. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-02]
• CABI, 2014. Azolla filiculoides [original text by Martin Hill]. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2020-02-28]
• Krippel, Y. & G. Colling, 2010. Notes floristiques. Observations faites au Luxembourg (2008- 2009). Bull. Soc. Nat. luxemb. 111: 11-32. [PDF 209 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-. Azolla filiculoides Lam. 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. Azolla filiculoides Lam. 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]
• Muller, S., 2006. Prolifération spectaculaire d’’Azolla filiculoides (Azollaceae, Pteridophyta) dans le canal de Jouy près de Metz (Lorraine, France) à l’automne 2005. Bull. Soc. Nat. luxemb. 107: 31-38. [PDF 828 Kb]
• Oly, M., 2022. Kartierung invasiver gebietsfremder Wasserpflanzen im Großherzotum Luxemburg, Untersuchungen zur Verbreitung von invasiven gebietsfremden Wasserpflanzen in einer beispielhaften Auswahl an Stillgewässern, Musée national d’histoire naturelle, Luxembourg. 117 pp. 
• 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 2023-08-17. Last proofread by Caroline Grounds on 2019-11-13.

	Juneberry	Status LU: established. 1st record: LU 1961, ITW <2000.
	Amerikanesch Leebirchen	Status Eur.: established. 1st record: FR ~1850-1900.
	Amélanchier d’amérique	RA: ISEIA: C1. Harmonia+: 0,07
	Kupfer-Felsenbirne	Wikipedia: | Wikispecies: | CABI
	Amerikans krentenboompje	Back to the list of neophytes

Brief description

In its introduced range, Amelanchier lamarckii F.G. Schroed. thrives on sandy, acidic soil, especially in heathlands, in open woodlands, along forest edges and in urban areas. Juneberry is apomictic and breeds true from seed. Fruits are dispersed by birds over long distances. Juneberry populations are slowly expanding in Western European countries (Belgium, Germany, Great Britain) and reported to be locally invasive. Juneberry can reduce the development of ground vegetation but it rarely forms dense monospecific stands. Outcompetition of native species is considered as unlikely. Impact on native vegetation is poorly reported in the scientific literature (Branquart et al. 2012).

Status and distribution in Luxembourg

Amelanchier lamarckii F.G. Schroed. was first reported as Amelanchier canadensis by Léopold Reichling on 1961-06-06 and 1961-06-08 from his garden in Avenue Guillaume, Belair, Luxembourg City (MNHNL 2000-a, LUXNAT Nr 48638).

The species was first observed in the wild by Yves Krippel on 2000-08-04  in the nature reserve Ditgesbaach near Ettelbruck (MNHNL 2000-b).

Amelanchier lamarckii was next recorded in Luxembourg by Krippel & Scheer (2006: 10) on 2003-09-04 on the western slope of Esch-sur-Sûre castle. The species is currently (2018) still present there (Krippel et al. 2019: 164). The next records date before 2008 and cannot be dated exactly as Welter et al. (2008: 62) list 4 undated locations.

In Luxembourg, juneberry is commonly planted as an ornamental tree, which is the case for the records of the species in the municipalities of Luxembourg City (Cents, Limpertsberg) and Hesperange (Welter et al. 2008: 62). In the municipality of Feulen, the species seems to be widely grown in gardens, squares and along streets (MNHNL 2000-c).

Juneberry is a melliferous species born in Europe from a North American strain (Lambinon & Verloove 2012: 373).

Juneberry is an apomictic microspecies, and presumed to be of hybrid origin (A. laevis and either A. arborea or A. canadensis) and therefore under the rules of botanical nomenclature it would be known as Amelanchier × lamarckii (Wikipedia contributors 2019).

Risk assessment

ISEIA protocol

C1 (1+2+2+1) (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,07 = (Overall Invasion score 0,57 x Overall Impact score 0,13) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum & F. Verloove, 2012. Harmonia database: Amelanchier lamarckii F.G. Schroed. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-16]
• CABI, 2009. Amelanchier lamarckii F.G. Schroed. [original text by Vicki Bonham]. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2019-11-22]
• Krippel, Y. & A. Scheer, 2006. Flore et végétation du château féodal d’Esch-sur-Sûre au Luxembourg. Bull. Soc. Nat. luxemb. 106: 3-16. [PDF 253 Kb]
• Krippel, Y., S. Schneider, A. Schopp-Guth & T. Walisch, 2019. Feuchtwiesen, Felsbiotope, Silikatmagerrasen, Burgen, Eichen-Niederwälder – Lebensräume auf Schiefer im Norden Luxemburgs. Tuexenia Beiheft 12: 137-187.
• 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-a. Recorder-Lux, database on the natural heritage of the Grand Duchy of Luxembourg. National Museum of Natural History, Luxembourg. Amelanchier lamarckii F. G. Schroeder observed on 1991-06-06, occurrence ID LUXNATFUND398819, via https://mdata.mnhn.lu [accessed 2021-01-13].
• MNHNL, 2000-b. Recorder-Lux, database on the natural heritage of the Grand Duchy of Luxembourg. National Museum of Natural History, Luxembourg. Amelanchier canadensis observed on 2000-08-04, occurrence ID DSS002920000069H, via https://mdata.mnhn.lu [accessed 2021-01-12].
• MNHNL, 2000-c. Amelanchier lamarckii F.G. Schroed. 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 2019-10-02]
• MNHNL, iNaturalist & GBIF, 2019. Amelanchier lamarckii F.G. Schroed. 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 2019-10-16]
• 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]
• 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, ISSN 1682-5519, 111 pp.
• Wikipedia contributors, 2019. Amelanchier lamarckii F.G. Schroed. in Wikipedia, The Free Encyclopedia, 11 September 2019, 16:47 UTC. URL: https://en.wikipedia.org/w/index.php?title=Amelanchier_lamarckii&oldid=915169386 [accessed 2 October 2019]

 Page content last updated on 2021-03-02. Last proofread by Caroline Grounds on 2019-11-13.

	Least duckweed	Status LU: casual. 1st record: LU & ITW 2002.
	Klinzeg Intelëns	Status Eur.: established. 1st record: FR 1965.1
	Lentille d’eau minuscule	RA: ISEIA: B1, Watch List. Harmonia+: 0,24.
	Winzige Wasserlinse	Wikipedia:  | Wikispecies: | CABI
	Dwergkroos	Back to the list of neophytes

Brief description

Lemna minuta Humb., Bonpl. et Kunth is an aquatic plant that settles in shallow standing or slow-flowing waters, often in shaded conditions. Outbreaks of the species cause dense floating mats at the water surface that reduce light penetration and gas exchanges, causing the predominance of respiratory activities and the reduction in dissolved oxygen in water beneath the mats. As for native duckweed species, outbreaks are usually limited in time and space and are favoured by increased levels of water eutrophication that often cause the disappearance of submerged macrophytes. Waterfowl and Cyprinid fish are known to eat duckweeds to supplement their diet which may help to reduce outbreaks (Branquart et al. 2010).

Status and distribution in Luxembourg

Lemna minuta Humb., Bonpl. et Kunth was first documented in Mecheren near Remerschen (Municipality of Schengen) close to the bird watch station on 21 June 2015 by Guy Colling and on 29 June 2015 by A. Mesterházy (Krippel & Colling 2016: 39; MNHNL 2000-). It should be noted that the tiny water lens had already been reported for the Remerschen ponds in 2002 by Gérard Schmidt (in litt.), but no herbarium specimens had been taken at that time (Krippel & Colling 2016: 39).

This American aquatic monocotyledon, the smallest species of its kind (Synonym: Lemna minuscula Herter), was discovered in the wild here in 1983 (Lambinon & Verloove 2012: 976). Given its pervasive potential, it was listed on the alert list (Ries et al. 2013).

Risk assessment

ISEIA protocol

B1 (2+3+2+3) = Watch List. Reassessed 16 February 2017 by Yves Krippel and Christian Ries. Assessment before the appearance of the species in Luxembourg: B0 (2+3+2+3) = Alert List (Ries et al. 2013).

Harmonia+ protocol

Overall risk score 0,24 = (Overall Invasion score 0,67 x Overall Impact score 0,35) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Branquart, E., I. Stiers, L. Triest, S. Vanderhoeven, W. Van Landuyt, F. Van Rossum & F. Verloove, 2010. Harmonia database: Lemna minuta Humb., Bonpl. et Kunth. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-11]
• CABI, 2021. Lemna minuta. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2021-03-04]
• Krippel, Y. & G. Colling, 2016. Notes floristiques. Observations faites au Luxembourg (2014-2015). Bull. Soc. Nat. luxemb. 118: 27-51. [PDF 1,33 MB]
• 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-. Lemna minuta Humb., Bonpl. et Kunth 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. Lemna minuta Humb., Bonpl. et Kunth 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]
• Oly, M., 2022. Kartierung invasiver gebietsfremder Wasserpflanzen im Großherzotum Luxemburg, Untersuchungen zur Verbreitung von invasiven gebietsfremden Wasserpflanzen in einer beispielhaften Auswahl an Stillgewässern, Musée national d’histoire naturelle, Luxembourg. 117 pp. 
• 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 2023-08-18. Last proofread by Caroline Grounds on 2019-11-19.

1. Cf. CABI 2021.[↩]

	Tree of heaven	Status LU: established. 1st record: LU <1875, ITW <2013.
	Himmelsbam	Status Eur.: established. 1st record: HU 1740s.  IAS of EU concern (2019).
	Ailante glanduleux	RA: ISEIA: C1. Harmonia+: 0,42.
	Götterbaum	Wikipedia: Wikispecies: | CABI
	Hemelboom	Back to the list of neophytes

Brief description

Ailanthus altissima (Mill.) Swingle is a fast-growing, light-demanding and thermophilic pioneer tree species. It grows best on nutrient-rich soils and is very tolerant to dryness and air pollution. It is mostly found in waste and disturbed areas, but can also invade different kinds of forest ecosystems, riparian areas, rock outcrops and semi-natural grasslands. Winged seeds are easily dispersed by wind and water over distances exceeding several hundreds of metres (Branquart et al. 2017).

Ailanthus altissima successfully displace native vegetation due to its rapid growth and root suckering. It produces allergenic toxins in bark and leaves. As these accumulate in the soil, they inhibit the growth of other plants (allelopathic interactions), favour the formation of monospecific stands and inhibit vegetation succession. Ailanthus also increases soil N content and pH. Ailanthus can reduce soil water availability in case of severe infestation. It may damage roads and other infrastructures due to strong and rapid root development (Branquart et al. 2017). The root system is aggressive enough to cause damage to sewers and foundations (GISD 2019).

Photo gallery

Alley of Alianthus altissima, Porte de France, Belval, Esch-sur-Alzette. Photos by Yan Steil, 23rd July 2014.

IAS of Union concern

In 2019, Ailanthus altissima was added to the list of invasive alien species of Union concern (Anonymous 2019) which implies that member states shall take all necessary steps to prevent it’s unintentional introduction or spread.

Status and distribution in Luxembourg

The oldest reference to Ailanthus altissima in Luxembourg is found in the flora of Krombach (1875: 108) who lists it as a cultivated species. To mention an old example, Jean Feltgen (1833-1904) included a specimen from a garden in Diekirch in his herbarium, unfortunately without mentioning a date (Specimen № 15467, MNHNL 2000-). It can still be considered the first documented record of the species before 1905, within Jean Feltgen’s lifetime.

The first documentation of the tree of Heaven in the wild dates from 2013, when Jerry Grün reports a grown specimen in a forest edge near Elvange (Ries & Krippel 2021). An earlier report on 13 July 1993 by Léopold Reichling in the Pfaffenthal district in Luxembourg City could not be verified as in the wild as it might have been part of the plantations in the gardens of the Hospice du Pfaffenthal (Obs. key: LUXNATFUND431045, MNHNL 2000-).

According to Lambinon & Verloove (2012: 463) the species is quite rare in urban areas (AR) and very rare in rural areas in the territory of the flora.

Ailanthus altissima is found in several parks in the country, including Tony Neuman Park (Hollman & Schroeder 1997: 22) and municipal park in Luxembourg City.

For two decades the species did not appear to have spread to the wild. It is only in recent years that the species was planted in several urban areas and appeared in the wild on sandstone cliffs in Luxembourg City (cf. also Krippel et al. 2020: 32).

In 2020, the salt-tolerant Ailanthus altissima was detected for the first time in a motorway median strip (A1 motorway near the port of Mertert, Yves Krippel, 2020-09-07, iNaturalist).

Considering the recent expansion of the species in Luxembourg and its probable future increased spread due to climate change, and to avoid major problems urban areas experience with the tree of Heaven as a weed across Europe, Ailanthus should not be planted any more as an ornamental tree and existing populations should be eradicated.

An identification sheet of the species has been published by the MECDD in French and German.

Ailanthus as ornamental tree in urban areas

• On 23rd July 2014 a complete alley of Ailanthus altissima was discovered in the street Porte de France in Belval / Esch-sur-Alzette. It was recently planted in the course of the regeneration of the brownfield site into a large scientific and cultural centre, including the science faculty of the University of Luxembourg (Steil 2014, pers. comm.). Based on sattelite photos the alley counts more than 70 individuals.
• A group of Ailanthus altissima trees was recently planted behind the Olympic swimming pool in the Kirchberg disctrict of Luxembourg City by the Fonds du Kirchberg. Seedlings have already started to spread on this site (Helminger 2018, pers. comm.).
• A row of 9 Ailanthus altissima was planted before 2008 along a parking area behind the church of Walferdange (Welter et al. 2008: 81; map).
• A single tree is present in the section of the municipal park situated between Avenue de la Porte-Neuve and Avenue Émile-Reuter in Luxembourg City (on the side of the Avenue de la Porte-Neuve in line with two trees of Corylus colurna. Two single trees can be found in the Rue du Rollingergrund, one in front of the house n°294 and another next to the residence on n°306 (Welter et al. 2008: 81).
• A single old tree with several saplings and a single younger grown-up tree were observed on 10th June 2018 in the municipal park of Diekirch situated along the river Sûre.
• A group of 4 Ailanthus altissima trees grow in a roundabout on the N6 road north of Mersch and several seedlings / young plants have been found in the commercial zone east of the roundabout (Yves Krippel, pers. comm. 2020-10-27).

In a few decades, with climate change helping, Ailanthus might grow in many pavement rinds, flowerbeds and vague grounds all over these sites and possibly into the wild in adjacent areas, as illustrated in the following example from planted tree in a roundabout north of Mersch:

Ailanthus in the wild

In 2018, three populations of Ailanthus altissima were sighted in the wild in Luxembourg City:

• on the edge of the cliff along the railway to Wasserbillig between the Plateau du Rham and the INS. As part of a site visit on 28/11/2019 with representatives of the Nature and Forestry Administration, Public Buildings and the MNHNL, it was decided that the management of this site will take place during winter 2019-2020 and that management should be continued until the site no longer represents a danger to the railway line below.
• on the edge of the Plateau du Rham southeast of the former military canteen;
• on the sandstone cliffs above n°11 Bisserweg (Grund district, Luxembourg City).

Management

A recent study in Berlin concludes that urban management strategies concerning Ailanthus would gain support from citizens when combining multiple approaches (Kowarik et al. 2021): (i) to control the species in case of realized negative impacts; (ii) to prevent the invasion of the species in areas of conservation concern; and (iii) to develop novel approaches of integrating wild Ailanthus trees into urban green spaces. These insights could support management measures that need to be established due to the EU-Regulation on Invasive Alien Species.

Action plan

The action plan dedicated to the tree of heaven, designed to limit the spread and minimise its in Luxembourg, was drafted in 2020 (Pfeiffenschneider & Hoppe 2020) and submitted for a 60 days lasting public consultation on 9 September 2020. It clearly postulates that, if its population continues to increase, this species is likely to cause ecological and economic damage.

• Finalised Action Plan for Ailanthus altissima (Pfeiffenschneider & Hoppe 2020)
• Page of public consultation (FR)

Risk assessment

ISEIA protocol

C1 (1+1+1+1) (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,42 = (Overall Invasion score 0,74 x Overall Impact score 0,57) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Anonymous, 2019. Commission implementing regulation (EU) 2019/1262 of 25 July 2019 amending Implementing Regulation (EU) 2016/1141 to update the list of invasive alien species of Union concern. Official Journal of the European Union L 199/1-2 (26.7.2019).
• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum & F. Verloove, 2017. Harmonia database: Ailanthus altissima (Mill.) Swingle. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-23]
• CABI, 2014. Ailanthus altissima (Mill.) Swingle [original text by Soraya Constán Nava]. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2019-11-26]
• GISD, 2019. Species profile: Ailanthus altissima in the Global Invasive Species Database. URL: http://www.iucngisd.org/gisd/speciesname/Ailanthus+altissima [accessed 2019-11-28]
• Hollman, A. & M. Schroeder, 1997. Parc Tony Neuman (Joyaux botanique au centre de la ville de Luxembourg, réalisé à partir de 1948 par Me Tony Neuman, notaire, Henri Luja, architecte-urbaniste, et Alphonse Hollman, jardinier en chef). AAT-Info 53, supplément. Éd. AAT – Garten und Teichfreunde Luxemburgs. Imprimerie Saint-Paul, Luxembourg. 64 pp.
• Kowarik I., T.M. Straka, M. Lehmann, R. Studnitzky & L.K. Fischer, 2021. Between approval and disapproval: Citizens’ views on the invasive tree Ailanthus altissima and its management. NeoBiota 66: 1–30. https://doi.org/10.3897/neobiota.66.63460
• 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]
• 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-. Ailanthus altissima 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 2018-01-08]
• Pfeiffenschneider, M. & Hoppe, F., 2020. Plan d’action pour espèces exotiques envahissantes au grand-duché de Luxembourg : Faux-vernis du Japon, Ailanthus altissima (Mill.) Swingle. Version 3.0 – 2020/09/20. Administration de la nature et des forêts, Luxembourg. 19 pp.
• Ries C. & Y. Krippel 2020. Ailanthus altissima (Mill.) Swingle – Distribution actuelle, recensement futur et mise en oeuvre des mesures d’éradication au grand-duché de Luxembourg. Rapport au Groupe de coordination sur les espèces exotiques envahissantes au Luxembourg (MECDD), Version 1.1 (2020-11-24). 9p.
• 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]
• 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, ISSN 1682-5519, 111 pp.

 Page content last updated on 2023-08-17. Last proofread by Caroline Grounds on 2019-11-12.

	American willowherb	Status LU: established. 1st record: LU & ITW 1950
	Drüse-Weideréischen	Status Eur.: established. 1st record: UK 1891.
	Épilobe à tige glanduleuse	RA: ISEIA: B3 – Watch List. Harmonia+: 0,15
	Drüsiges Weidenröschen	Wikipedia: | Wikispecies: | CABI
	Beklierde basterdwederik	Back to the list of neophytes

Brief description

Epilobium ciliatum Raf. is a pioneer plant species that thrives mainly in man-made environments such as arable land, gardens, tree nurseries, clearcuts and ruderal areas. It may also become established in open riparian habitats. Its seeds are adapted for wind dispersion and have a high germination rate. It is one of the arable weed species with the highest rate of increase in Europe (Branquart et al. 2010).

Status and distribution in Luxembourg

Epilobium ciliatum Raf. was first documented under its synonym Epilobium adenocaulon Hausskn. on 1950-07-19 in wasteland on sand between two spruce stands near Croix-des-Bourgeois (Biergerkräiz) near Bridel (municipality of Kopstal) by François Léon Lefort (1917-1975) and Léopold Reichling (1921-2009) (Reichling 1961: 68ff.; MNHNL 2000-; herbarium specimen N°17920).

The species, described by Haussknecht in 1879 based on American herbarium samples, is native to North America where it is widely distributed as several varieties that are difficult to define. Introduction in Europe: < 1900 (Great Britain, Russia), 1900 (Sweden), 1915 (Netherlands), 1916 (Finland), 1931 (East Prussia), 1950 (Luxembourg), 1952 (Belgium, France) (Reichling 1961: 74).

This North American plant species was naturalised in Europe around 1900; it is rapidly expanding (Lambinon & Verloove 2012: 434).

700 records of the species are listed in the MNHNL-mdata online portal and the plant is widespread throughout the country (MNHNL, iNaturalist & GBIF 2019).

Risk assessment

ISEIA protocol

B3 (3+3+2+1) = Watch List (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,15 = (Overall Invasion score 0,69 x Overall Impact score 0,22) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum, F. Verloove, 2010. Harmonia database: Epilobium ciliatum Raf.. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-09]
• CABI, 2019. . In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2020-02-28]
• 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-. Epilobium ciliatum Raf. 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. Epilobium ciliatum Raf. 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]
• Reichling, L., 1961. Notes floristiques 1957-1958. Bull. Soc. Nat. luxemb. 63: 19-99. [PDF 4612 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]

 Page content last updated on 2021-03-03. Last proofread by Caroline Grounds on 2019-11-17.

	Bohemian Knotweed	Status LU: established. 1st record: LU & ITW 2005.
	Béimescht Knuetkraut	Status Eur.: established. 1st record ITW UK 1954.
	Renouée de bohême	RA: ISEIA: B1 – Watch List. Harmonia+: 0,59
	Bastard-Knöterich	Wikipedia: | Wikispecies: n/a | CABI
	Boheemse duizendknoop	Back to the list of neophytes

Brief description

Like other Asiatic knotweeds, Fallopia ×bohemica (Chrtek & Chrtková) J. P. Bailey 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. The Bohemian knotweed may produce seeds but seedling establishment is usually inefficient due to frost sensitivity. 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 xbohemica exhibits hybrid vigour and is reputed to be more invasive than the two parents, F. japonica and F. sachalinensis. It typically forms very dense stands, excluding native vegetation and prohibiting regeneration. It reduces plant and invertebrate species diversity, alters the habitat for wildlife, and changes light and energy conditions of the ecosystem. Once stands become established, they are extremely persistent and difficult to remove. Its development can favour river bank erosion during the winter (Branquart et al. 2010).

Uncertain status of Fallopia × bohemica 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 international 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

Fallopia ×bohemica (Chrtek & Chrtková) J. P. Bailey was first documented in Luxembourg in the wild by Daniel Thoen on 2005-10-05 on the outskirts of the village of Saeul (Saintenoy-Simon et al. 2008: 32). The species was next reported by Manou Pfeiffenschneider on 2016-09-17 near Wilspull (Municipality of Bourscheid) (MNHNL 2000-).

Currently, 16 records of the hybrid are accessible through the MNHNL-mdata portal (MNHNL, iNaturalist & GBIF 2019). As far as we currently know, the species is distributed along the rivers Mamer, Black Ernz and Gander.

As in the case of Fallopia sachalinensis, the frequency of male-sterile and male-fertile colonies in the environment should be specified. This hybrid, long unknown, is very variable. It could have been formed by spontaneous hybridisation of both parents; but the introduction by horticulturists of hybrid strains is equally, if not more likely (Lambinon & Verloove 2012: 193).

As outlined in the section above, the status of the species has to be revised, as many records could have been misidentified, which is why we describe both Bohemian and Japanese knotweed together in the following section.

Importance and distribution of Bohemian and Japanese 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

B1 (2+2+3+3) = Watch List (Ries et al. 2013: 18). Needs to be reassessed (see above).

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

• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum, F. Verloove & A. Vervoort, 2010. Harmonia database: Fallopia ×bohemica (Chrtek & Chrtková) J. P. Bailey. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-09]
• 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]
• CABI, 2019. Fallopia x bohemica. 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 470 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, iNaturalist & GBIF, 2020. Fallopia ×bohemica 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 2020-03-02]
• 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 400 KB]
• Pfeiffenschneider, M., P. Gräser & C. Ries, 2014. Distribution of selected neophytes along the national railway network of Luxembourg. Bull. Soc. Nat. luxemb. 115: 95-100. [PDF 1457 KB]
• 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]
• Saintenoy-Simon, J. et coll., 2008. Trouvailles floristiques récentes (2006-2007). Adoxa 59: 17-52.

 Page content last updated on 2021-03-04. Last proofread by Caroline Grounds on 2019-11-20.

	Jerusalem artichoke	Status LU: established. 1st record: LU ~1720, ITW <1875.
	Topinambur, Russesch Gromper1	Status Eur.: established. 1st record: UK 1607.
	Topinambour	RA: ISEIA: B2, Watch List. Harmonia+: 0,47.
	Topinambur	Wikipedia: | Wikispecies: | CABI
	Aardpeer	Back to the list of neophytes

Brief description

Helianthus tuberosus L. is a plant that prefers well-lit, sandy, moist and nutrient-rich soils. It grows best in habitats repeatedly disturbed by floods (riparian areas) but may also occur in ruderal and agricultural environments. In western European climatic conditions, the plant does not produce viable seeds and propagates vegetatively. Tubers and pieces of rhizomes are transported with rodents and flowing water, especially winter floods. The plant can produce dense and persistent monospecific populations along rivers, where it outcompetes native species, slows down natural colonisation by trees and favours river bank erosion. It can be a weed of agricultural fields either by invading the fields or by reducing the yield of consecutive crops.

Introduction in Luxembourg

The Jerusalem artichoke arrived in Luxembourg at the beginning of the 18th century. In his seminal work “La pomme de terre en Wallonie au XVIIIe siècle” (1976), the Belgian historian Fernand Pirotte draws the following conclusions (Pirotte 1976 cit. in Massard 2009):

1. at the beginning of the 18th century, a first previously unknown tuber plant, the Jerusalem artichoke, probably originating from Lorraine, was introduced into the Duchy of Luxembourg under its name “pomme de terre” (earth apple), which was commonly used in Lorraine.
2. around 1715-1720, another tuber plant, the potato, the ‘poire de terre’ or ‘Grundbirne’, was imported from the Rhineland (later the Rhine province) and was called ‘crompire’ or ‘grompir’ by the people.
3. the two species coexisted for some time, with a rapidly increasing dominance of the potato, which overtook Jerusalem artichoke within 20 to 25 years, before 1740. In the 1750s, or at the beginning of the 1760s at the latest, the potato has definitely replaced the Jerusalem artichoke. Paradoxically, the authorities retained the designation “topinambour”, but from about 1740/50 onward they used it for the potato, which they had virtually ignored until then, since its cultivation had been limited to gardens and had thus remained tithe-free.

Status and distribution in Luxembourg

“It seems that the introduction of this tuber, also originating from the New World, dates from the same period as the potato [~1725], and that by the middle of the last century [1750] its cultivation was proportionally more widespread than today” (Fischer 1860: 143; 1872: 77-78). But there may be a confusion of names, as potato cultivation was introduced in the 1720s under the name of topinambour or “ground pear” (De la Fontaine cit. in Fischer 1860: 143).²

In 1741 the tithe (tax) was already raised on the Jerusalem artichoke (Ozeray 1827: 267).

In the middle of the 19th century, “Jerusalem artichokes[…] are so little cultivated in the Grand Duchy that the vast majority of farmers do not yet know its tubers. It is even regrettable that the resources that Jerusalem artichokes can offer in certain circumstances have not yet been fully appreciated” (Fischer 1860: 143).³

Helianthus tuberosus was locally cultivated in Luxembourg throughout the 19th century (Löhr 1844: 126, Fischer 1872: 77), especially around Greisch and Ansembourg castle (Tinant 1836: 434). Krombach (1875: 331) states it is sometimes grown in sandy soils and then occurs also subspontaneously.

The first documented observation of the species in Luxembourg dates from 1880. On 21st October 1880, the Société de botanique collected a specimen from a garden in Dommeldange, north of Luxembourg City (Specimen nr. LUX003675, MNHNL 2000-). The first documented observation of the species in the wild dates from 1956. It was found by Léopold Reichling on 30th September 1956 in Born in the municipality of Mompach (MNHNL 2000-). There are 427 observations in the Recorder-Lux database (MNHNL, iNaturalist & GBIF 2019).

According to Lambinon & Verloove (2012: 720), it grows in banks, gravel and mud banks along watercourses, often in large stands, is naturalised in the Lorraine district (rivers Chiers, Moselle and tributaries (AR), but locally very abundant; elsewhere rare (R), subspontaneous or locally naturalised. Rarely cultivated in gardens, especially in the past, for its edible but generally not very appreciated tubers, nowadays sometimes in fallows, for feeding game.

The Jerusalem artichoke is widely distributed along the Lower Alzette, the Lower Sûre and the Moselle. Along the Alzette, important populations of the species often appear at the edge of corn fields.

Risk assessment

ISEIA protocol

B2 (2+3+2+2) = Watch List (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,47 = (Overall Invasion score 0,88 x Overall Impact score 0,53) (Ries et al. 2020).

Worldwide distribution

Bibliography

• CABI, 2019. Helianthus tuberosus. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2020-03-02]
• 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.
• Krippel, Y. & G. Colling, 2006. Notes floristiques. Observations faites au Luxembourg (2004-2005). Bull. Soc. Nat. luxemb. 107: 89-103. [PDF 288 Kb]
• 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.
• Löhr, M. J., 1844. Taschenbuch der Flora von Trier und Luxemburg : mit Berücksichtigung der Nahe- und Glan-Gegenden. 319 S. Trier, Verlag C. Troschel.
• Massard, J. A., 2009. 300 Jahre Kartoffel in Luxemburg: (I) Europa entdeckt die Kartoffel. (II) Grundbirne, Grompir, Gromper: die Kartoffel erobert Luxemburg. (III) Die Kartoffel in Luxemburg im 19. Jh. Artikel aus: Lëtzebuerger Journal 2009, [I] Nr. 15 (22. Jan.): 23; Nr.16 (23. Jan.): 10, Nr. 17 (24./25. Jan.): 11; [II] Nr. 18 (27. Jan.): 23, Nr. 19 (28. Jan.): 21; [III] Nr. 20 (29. Jan.): 9, Nr. 21 (30. Jan.): 21.
• MNHNL, 2000-. Helianthus tuberosus 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. Helianthus tuberosus 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 2019-09-05]
• Ozeray, M.-J.-F., 1827. Histoire des pays, château et ville de Bouillon depuis l’origine du Duché jusqu’à la révolution de 1789. 348 p. Imprimerie J. Lamort, Luxembourg. (1re édition) [online source]
• 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]
• Pirotte, F., 1976. La pomme de terre en Wallonie au XVIIIe siècle. Liège, Editions du Musée wallon, 87 p. (= Collection d’études publiée par le Musée de la vie wallonne, 4).
• 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]
• 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.

 Page content last updated on 2021-03-04. Last proofread by Caroline Grounds on 2019-11-18.

1. Cf. Krombach 1875: 331.[↩]
2. Original text: « Il faut croire que l’introduction de ce tubercule, aussi originaire du nouveau monde, date de la même époque que la pomme de terre, et que vers le milieu du siècle dernier la culture en était proportionnellement plus répandue qu’aujourd’hui. » (Fischer 1860: 143) Mais il se peut qu’il y ait une confusion de noms, la culture de la pomme de terre ayant été introduite dans les années 1720 sous le nom de topinambour ou poire de terre (De la Fontaine cit. in Fischer 1860: 143).[↩]
3. Original text: « Les topinambours […] sont si peu cultivés dans le Grand-Duché, que l’immense majorité des laboureurs n’y connaissent pas encore ses racines. Il est même à regretter qu’on n’ait pas jusqu’ici apprécié à leur juste valeur les ressources que le topinambour peut offrir dans certaines circonstances » (Fischer 1860: 143).[↩]

	Garden lupin	Status LU: established. 1st record: LU <1901, ITW 1991.
	Gaarde-Luppéng	Status Eur.: established. 1st record: UK 1826.1
	Lupin des jardins	RA: ISEIA: C1. Harmonia+: 0,26.
	Vielblättrige Lupine	Wikipedia: | Wikispecies: | CABI
	Vaste lupine	Back to the list of neophytes

Brief description

The pioneer and ruderal plant Lupinus polyphyllus Lindl. prefers medium-moist and shaded sites, with a nutrient-poor sandy or loamy soil. It is found in riparian habitats, abandoned grasslands, forest clearings, clearcuts and on road verges. The strong invasion of semi-natural habitats, as it can be seen in Scandinavia for example, has so far been reported only rarely in western Europe. Seeds are dispersed in the immediate vicinity of the mother plant.

L. polyphyllus may occur in extensive, rather dense stands. It reduces the diversity of early successional plant communities, but has little effect on later successional stages. In central Europe, the plant replaces species-rich dry acidic grasslands with monocultures. Due to the nitrogen-fixing nodules it may change the soil chemistry in favour of nitrogen-demanding species; eutrophication of nutrient-poor sites and consequent changes in community structure and diversity is the main problem when it invades an area (Branquart et al. 2010).

Status and distribution in Luxembourg

Lupinus polyphyllus Lindl. was first mentioned at a meeting of the Luxembourg Naturalist Society on 1901-05-19 in Diekirch: “Mr. Klein ² shows: (1) a specimen of Lupinus polyphyllus, a perennial plant that overwinters and, because it is very rich in nitrogen, is most suitable for green manure. […]” (Bricher 1901: 179).

The oldest herbarium specimen at the Museum was collected in June 1949 by Jos. Witry in a garden in Bergem (Specimen № 51392, MNHNL 2000-).

Lupinus polyphyllus Lindl. was first documented in the wild in Luxembourg by Yves Krippel (1992) in the forest Bambësch in Luxembourg City. The species was next documented in the wild by Guy Colling on 2002-06-15 during the Biodiversity Weekend 2002 in the municipality of Bettembourg (MNHNL 2000-).

While only few records of the species were listed in the MNHNL-mdata online portal (MNHNL, iNaturalist & GBIF 2019) a few years ago, more and more occurences of L. polyphyllus have been documented recently.

The melliferous garden lupin originates from western North America. Under the name of Lupinus polyphyllus several species, hybrids or cultivars may be confused; next to L. polyphyllus s. str., characterised by the entire upper lip of the calyx, one could observe L. perennis L., L. nootkatensis Donn ex Sims and L. ×regalis Bergm. (L. arboreus Sims × polyphyllus), recognisable by the emarginated upper lip of the calyx (Lambinon & Verloove 2012: 392).

Risk assessment

ISEIA protocol

C1 (1+2+2+2) (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,26 = (Overall Invasion score 0,55 x Overall Impact score 0,47) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum, F. Verloove & A. Vervoort, 2010. Harmonia database: Lupinus polyphyllus Lindl.. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-11]
• Bricher, E., 1901. Wanderversammlung in Diekirch am 19. Mai. Bulletin de la Société des Naturalistes Luxembourgeois 11 (6): 178-183.
• CABI, 2021. Lupinus polyphyllus. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2021-03-04]
• Krippel, Y., 1992. Effets à court terme d’un apport de fertilisants sur la forêt du Bambësch (Luxembourg-Ville). Travail de fin d’études d’Ingénieur agronome à l’Université Libre de Bruxelles (ULB), section interfacultaire d’agronomie, orientation agronomie générale. [mémoire non publié].
• 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-. Lupinus polyphyllus Lindl. 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. Lupinus polyphyllus Lindl. 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]
• 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 2022-06-14. Last proofread by Caroline Grounds on 2019-11-19.

1. Cf. CABI 2021.[↩]
2. Ed.: Edmond Joseph Klein (1866-1942)[↩]

	Oregon-grape	Status LU: established. 1st record: LU 1842, ITW <1875.
	Gewéinlech Mahonie	Status Eur.: established. 1st record: 1822.1
	Mahonia faux houx	RA: ISEIA: B1 – Watch List. Harmonia+: 0,35.
	Gewöhnliche Mahonie	Wikipedia: | Wikispecies: | CABI
	Mahonie	Back to the list of neophytes

Brief description

The shrub Mahonia aquifolium (Pursh) Nutt. (Syn.: Berberis aquifolium Pursh.) occurs in a wide range of semi-natural habitats like dunes, rock outcrops, grasslands and woodlands. They prefer calcic soils and can grow in dry to moist conditions, often in shaded habitats. Mahonia produces numerous flowers and berries that are dispersed by birds over long distances. The recent expansion of this species in western Europe is probably triggered by climate warming.

Mahonia aquifolium has a high growth rate due to hybridisation and subsequent selection by breeders. Rapid clonal growth takes place through root suckers and stem layering, leading to the formation of large and dense populations that are known to overgrow and outcompete native species and accelerate the colonisation of open habitats by woody vegetation (Branquart et al. 2010).

Status and distribution in Luxembourg

Mahonia aquifolium (Pursh) Nutt. is a common ornamental plant in Luxembourg which regularly escapes from cultivation in private and public gardens to form spontaneous woody vegetation. While documented occurrences in the wild remained rare until a few years ago the actual distribution map seems to indicate that uncultivated populations of the species are much more common now.

Koltz (1875:18) reports that the species was introduced into the Walferdange Park in 1842 (= 1st record); furthermore, it sometimes occurs subspontaneously, e.g. in the fir grove above the Jewish cemetery in Clausen (Luxembourg City), which is why we consider <1875 as the date of 1st record in the wild.

It was next documented in the wild in Luxembourg on 1950-07-20 by Léopold Reichling (1921-2009) in Verluerekascht (Municipality of Larochette) (MNHNL 2000-).

The oldest herbarium specimen at the MNHNL was collected by Jos. Witry on 1935-04-21 in a park in Bergem (Specimen № 51941, MNHNL 2000-).

The melliferous Oregon-grape originates from North America (Lambinon & Verloove 2012: 92).

Other Mahonia species, cultivars and hybrids

Various cultivars and hybrids of this species are planted for ornamental purposes, the latter resulting from hybridisation with other North American species Mahonia pinnata (Lag.) Fedde and M. repens (Lindl.) D. Don in particular. The following taxa could thus be observed escaping from culture: M. aquifolium, M. ×wagneri (Jouin) Rehd. (M. aquifolium × pinnata) and M. ×decumbens Stace (M. aquifolium × repens) (Lambinon & Verloove 2012: 92).

Krombach (1875: 38) mentions Mahonia repens (Lindl.) G.Don for Luxembourg: “Introduced from America and cultivated for its early flowering and evergreen foliage.”

In total, Jean-Pierre-Joseph Koltz (1875: 18) mentions six Mahonia species introduced to Luxembourg:

• Mahonia aquifolium (Pursh) Nutt.: introduced into the Walferdange Park in 1842;
• Mahonia fascicularis DC.: introduced into the Walferdange Park in 1842;
• Mahonia fortunei (Lindl.) Fedde: introduced into the Dominican Park in 1853;
• Mahonia japonica (Thunb.) DC.: introduced into the Dominican Park in 1854;
• Mahonia nervosa (Pursh) Nutt.: introduced into the Dominican Park in 1861;
• Mahonia repens (Lindl) G. Don: introduced into the Walferdange Park in 1842.

Risk assessment

ISEIA protocol

B1 (3+2+2+2) = Watch List (Ries et al. 2013: 18). Because of the growing number of documented observations the ISEIA evaluation should probably be changed to B2.

Harmonia+ protocol

Overall risk score 0,35 = (Overall Invasion score 0,72 x Overall Impact score 0,48) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Branquart, E., S. Vanderhoeven, W. Van Landuyt, F. Van Rossum, F. Verloove & A. Vervoort, 2010. Harmonia database: Mahonia aquifolium (Pursh) Nutt.. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-11]
• CABI, 2021. Mahonia aquifolium. In: Invasive Species Compendium. Wallingford, UK: CAB International. URL: www.cabi.org/isc [accessed 2021-03-04]
• Koltz, J.-P.-J., 1875. Dendrologie luxembourgeoise. Catalogue des arbres, arbrisseaux et arbustes spontanés, subspontanés ou introduits dans la culture du Grand-Duché de Luxembourg. Imprimerie V. Buck, Luxembourg, 217 pp.
• 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-. Mahonia aquifolium (Pursh) Nutt. 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. Mahonia aquifolium (Pursh) Nutt. 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]
• 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 2023-05-05. Last proofread by Caroline Grounds on 2019-11-19.

1. Cf. CABI 2021.[↩]

	Cherry laurel	Status LU: established. 1st record: LU <1875, ITW 1989.
	Lorber-Kiischtebam	Status Eur.: established. 1st record: IT ~1550.
	Laurier-cerise	RA: ISEIA: B3, Watch List. Harmonia+: 0,45.
	Lorbeer-Kirsche	Wikipedia: | Wikispecies:
	Laurierkers	Back to the list of neophytes

Spot the cherry laurel – citizen science with children

The Department of Ecology of MNHNL carried out a citizen science survey with children who are members of the Panda Club of the Luxembourg National Museum of Natural History (Schaltz 2017). See the post Spot the cherry laurel – A citizen science survey with children for more details.

Brief description

Prunus laurocerasus L. is a shrub that thrives in woodland areas with moist, slightly acidic soils, both in well-lit and shaded conditions. Fruits are dispersed over long distances by birds. In recent years, seedlings have increasingly been observed in the wild.

So far, strong invasion by cherry laurel is not known in western Europe. Invasion histories are, however, numerous in southern and central Europe, where the plant rapidly expands by root-suckering, layering and stump-sprouting. It has a dense and permanent canopy that outcompetes native species, prevents forest regeneration and reduces biodiversity. Elevated atmospheric CO2 concentration and global warming recently favoured plant installation in Atlantic conditions as well, where it is likely to become a new threat for native biodiversity. The plant is a potential vector of different Phytophtora pathogens. Leaves contain cyanogenic glucoside that are toxic for humans (Branquart et al. 2010).

A field survey in the region of Basel, Switzerland, assessed the impact of the invasive shrub Prunus laurocerasus on the native vegetation and soil properties in suburban deciduous forests. A lower native plant species richness in both the ground vegetation and shrub layer was observed in plots with presence of P. laurocerasus. A different species composition of the ground vegetation was also found among plots with and without the invasive shrub. Plots invaded by P. laurocerasus had a lower soil moisture content than control plots. The intensity, diversity and substrate richness of the carbon sources were elevated in soil from invaded plots compared to soil in control plots. However, the chemical soil characteristics examined and the activities of enzymes were not influenced by the invasive plant. The effects of P. laurocerasus became more pronounced with the time elapsed since the establishment of the invasive plant. Thus, the removal of young P. laurocerasus individuals would be an appropriate management practice for this invasive shrub species (Rusterholz et al. 2018).

Picture galleries

Prunus laurocerasus near the natural reserve Haard – Hesselsbierg – Staebierg, Dudelange. Photos by Tiago de Sousa (ANF), 15 March 2017.

Disposal of hedge cuttings of Prunus laurocerasus in the forest at the edge of the road between Meysembourg and Angelsberg. Photos: C. Ries, 2021-03-12.

Status and distribution in Luxembourg

Koltz (1875: 55) lists Prunus laurocerasus L. under its synonym Padus laurocerasus (L.) Mill. as cultivated for a long time. Krombach (1875: 145) lists the species under its synonym Cerasus laurocerasus DC. as a cultivated evergreen shrub.

The oldest herbarium specimen at the MNHNL was collected in 1952 by Adolphe Molitor in Höhenhof near Luxembourg City (Specimen № MNHNL34303, MNHNL 2000-).

Kariger states “This ornamental shrub, which originates from south-eastern Europe and often runs wild in the Mediterranean region and in western France, is rarely found in this condition in our country”. He then reports first observations in the wild for Luxembourg: the variety with narrow-pointed, sharply toothed leaves in late 1989 (seminary garden on the Würthsberg in Clausen, Luxembourg City; Kuebebierg near Weimerskirch) (Kariger 1990: 86) and the variety with oval leaves in 1990 (Pulvermühl, Luxembourg City; Schlaed, Dommeldange) (Kariger 1990: 94).¹

Since 2017, the plant was discovered in forest areas west of Steinsel, between Steinsel and Bridel, in Bereldange, close to the Haard – Hesselsbierg – Staebierg nature reserve next to Dudelange, near Cruchten (Krippel et al. 2018: 70). Since then, further locations have been found which suggest that the species is expanding into the wild (e.g. Findel, Remich). A similar behaviour can be observed in neighbouring Belgium (Henneresse 2014).

Currently, 120 records (2019: 75) of the cherry laurel are accessible through the MNHNL-mdata portal (MNHNL, iNaturalist & GBIF 2021). This trend confirms this species is more and more often observed far from any dwelling (Krippel et al. 2020: 45).

Nowadays in Luxembourg, cherry laurel is a common garden plant, mostly planted to build hedges.

Management

Since 2020, a project has been running on behalf of the MNHNL in cooperation with two forestry offices to map Prunus laurocerasus in their forest areas and to develop control methods: in principle, small specimens are uprooted, medium-sized ones are dug up and large ones are curled. The experience and knowledge gained have been incorporated into control recommendations. A manual has been prepared in German, French and Portuguese.

Initial mapping shows that the species has spread rapidly in recent times.

Management in the Steinsel forestry district

The cherry laurel is mainly found on the Luxembourg sandstone plateaus, usually around nurseries and on the outskirts of settlements. In general, a main plant establishes itself in the forest and multiplies horizontally by shoots. Removal from sandy soil is fairly easy and allows the plant to be removed almost entirely.

About 30 cherry laurel plants were removed in the Steinsel forest district in 2020. The removal of this plant is done manually, with simple tools (square cross pick, spade). Moving through the forest is done on foot. The uprooted cherry laurels are then thrown into a communal “household waste” container which will be transferred to the SIDOR incineration plant in Leudelange. The only thing left to do is to check the areas for rootlets later (Lichtenberger 2020).

Cultivated evergreen Prunus species and cultivars

Two species of hardy, evergreen Prunus are grown for ornamental purposes in parks and gardens: P. laurocerasus L. (Syn.: Laurocerasus officinalis M.J. Roem.) [of which two varieties are mainly cultivated: P. laurocerasus var. caucasica (Kirchner) Jaeger and P. laurocerasus var. schipkaensis Späth ex H. Späth] and P. lusitanica L. [Syn. : Laurocerasus lusitanica (L.) M.J. Roem.] ; these two species are sometimes observed in a subspontaneous state, the first more and more often, the second very rarely (Lambinon & Verloove 2012: 365).

Native hedge plants as alternatives to the cherry laurel

The following species are good alternatives² for creating a privacy hedge:

• Carpinus betulus: leaves deep green, bright yellow to brown in autumn; there are varieties that lose their leaves only at the end of winter.
• Fagus sylvatica: orange-red leaves in autumn; there are varieties that lose their leaves only at the end of winter.
• Acer campestre: grows quickly, popular for higher hedges.
• Prunus spinosa: dense hedge; good retreat and food source for animals; fruits can be harvested after the first night frosts and made into jam or liqueur.
• Cornus mas: three to six metres high; flowers from February, valuable food for bees; leaves yellow to orange in autumn; red, edible fruits very rich in vitamins; good protective hedge for birds.
• Corylus avellana: up to 7 m high; from late January to April it forms flowers in golden-yellow catkins; pollen allergy sufferers should avoid these plants, however, as the male catkins release a lot of pollen; nuts are a food source for native wildlife, birds use the hedge for nesting.
• Sorbus aucuparia: up to 15 m high, red fruit clusters in autumn; berries are eaten by many bird species; very rich in vitamins.

Risk assessment

ISEIA protocol

B3 (3 + 2 + 2 + 2) = Watch list, reassessed on 2021-03-21 by C. Ries & M. Pfeiffenschneider. First assessed as C1 (2+2+0+1) (Ries et al. 2013: 18).

Harmonia+ protocol

Overall risk score 0,45 = (Overall Invasion score 0,70 x Overall Impact score 0,63) (Ries et al. 2020).

Worldwide distribution

Bibliography

• Branquart, E., P. Dupriez, S. Vanderhoeven, W. Van Landuyt, F. Van Rossum & F. Verloove, 2010. Harmonia database: Prunus laurocerasus L.. Harmonia version 1.2, Belgian Forum on Invasive Species. URL: http://ias.biodiversity.be [accessed on 2019-10-15]
• GBIF 2020. Prunus laurocerasus in GBIF Secretariat (2019). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2020-03-02.
• Henneresse, T., 2014. Notes floristiques inédites sur la Lorraine belge et l’Ardenne méridionale (2009–2013). Adoxa 81: 29-40.
• Kariger, J.-J., 1990. Auf der Suche nach Seltenheiten und verschwundenem 1970-1989. Bericht und Auswahl floristischer Tätigkeit ergänzt durch ökologische Betrachtungen.. Bulletin de la Société des naturalistes luxembourgeois 90: 71-101. [PDF 1762 KB]
• Koltz, J.-P.-J., 1873. Prodrome de la flore du grand-duché de Luxembourg. Première partie. Plantes phanérogames. Imprimerie V. Buck, Luxembourg. 279 S.
• 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]
• 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.
• Lichtenberger, G., 2020. Traitement de Prunus laurocerasus dans le triage forestier de Steinsel, Luxembourg. Rapport non publié, 2020-10-22, 4 pp.
• MNHNL, 2000-. Prunus laurocerasus 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 2019-10-15]
• MNHNL, iNaturalist & GBIF, 2021. Prunus laurocerasus 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 2021-01-13]
• 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]
• Rusterholz, H.P., J. Schneuwly, B. Baur, 2018. Invasion of the alien shrub Prunus laurocerasus in suburban deciduous forests: Effects on native vegetation and soil properties. Acta Oecologica 92, 44-51.
• Schaltz, Michèle, 2017. Fuerschung am ‘Natur Musée’: Ekologie. Panewippchen 4: 6-11. [PDF 2.2 MB]

 Page content last updated on 2023-03-14. Last proofread by Caroline Grounds on 2021-03-26.

1. Original text: “Dieser aus Südosteuropa stammende Zierstrauch, der im Mittelmeergebiet und in Westfrankreich häufig verwildert, ist bei uns nur selten in diesem Zustand anzutreffen.
   Am 2.12.1989, nicht selten am schattig-feuchten, mit Mischwald bestandenen Westhang des Clausener Würthsberg (‘Seminärsgaard’).
   Am 11.12.1989 im thermophilen Eichen-Haselstrauchgestrüpp am Südhang des ‘Kuebebierg’ bei Weimerskirch. Einige Schösse. Beide Standorte auf Lux. Sandstein. Vorgefundene Varietät jedesmal die der schmalspitzen, scharfgezähnten Blätter.” (Kariger 1990: 86)
   “Am 1.2.1990, zerstreut, auf Pulvermühl eingebürgert vorgefunden; waldiger Nordwesthang zum “Hammerdällchen”, Carpinion mit Quercion pubescentis-Elementen. Lux. Sandstein. Etwa um dieselbe Zeit, zerstreut, “Schlaed” bei Dommeldingen; Fagion sylvaticae auf Lux. Sandstein. An diesen beiden Orten Varietät mit ovalen Blättern.” (Kariger 1990: 94)[↩]
2. Source: https://www.haus.de/garten/heckenpflanzen-8-alternativen-zum-kirschlorbeer[↩]