Potentilla norvegica L. (Euras., N Am.) – A rare but slightly increasing, locally naturalized alien. Already recorded in the 19th century but its genuine naturalization started much later than that of P. intermedia. The earliest cases of local naturalization were documented since the 1940’s when it was collected near Charleroi (since 1943: coal mining spoil heaps), Boitsfort (since 1945: by railway tracks) and Brecht (since 1946: heathland, military area). Similarly, it is known since many decades from, for instance, Averbode (1954), Borinage area (numerous localities since 1952), coal mining area around Genk (1960’s), etc. At present P. norvegica is well naturalized in Flanders in the Kempen and in the Antwerp area (Verloove 2002, Verloove 2006). It is less rare in Wallonia; especially in the Borinage area it is not rare. Potentilla norvegica often grows along with the similar P. intermedia but it is much less widespread (Verloove 2002, Verloove 2006).
The vector of introduction of Potentilla norvegica is uncertain. At least between 1915 and 1946 it was sometimes recorded as a wool alien in the surroundings of Verviers. Recent records are often associated with cereals.
Potentilla norvegica is a variable species but its infraspecific variability is poorly studied in Belgium. According to Lambinon & Verloove (2012) subsp. hirsuta (Michaux) Hyl., with obovate to almost circular leaflets, is the usual taxon. It is native in North America, while subsp. norvegica is an Old World taxon (Eurasia).
Although often confused in herbaria, Potentilla norvegica is well-separated from P. intermedia and allies. This was also confirmed in a macro- and micromorphological analysis (Leht & Paal 1998).
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Selected literature:
Arnold H. (1981) Ein neuer Fundort von Potentilla norvegica L. in Mittelhessen. Hessische Floristische Briefe 30(4): 55-56.
Asker S. (1970) Apomictic biotypes in Potentilla intermedia and P. norvegica. Hereditas (Lund) 66: 101-107.
Ertter B., Elven R., Reveal J.L. & Murray D.F. (2014) Potentilla. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 9. Oxford University Press, New York-Oxford: 121-218. [available online at: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=126635]
Lambinon J. & Verloove F. (avec coll. Delvosalle L., Toussaint B., Geerinck D., Hoste I., Van Rossum F., Cornier B., Schumacker R., Vanderpoorten A. & Vannerom H.) (2012) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Sixième édition. Jardin botanique national de Belgique, Meise: CXXXIX + 1195 p.
Leht M. & Paal J. (1998) Potentilla L. sect. Rivales Wolf and related taxa in the Baltic States. Folia Geobot. 33: 171-186.
Richter H. (1955) Potentilla norwegica L. als Neueinwanderer im Dillkreis. Hessische Floristische Briefe 4: 211-212.
Verloove F. (2002) Ingeburgerde plantensoorten in Vlaanderen. Mededeling van het Instituut voor Natuurbehoud n° 20: 227 p.
Verloove F. (2006) Potentilla norvegica. In: Van Landuyt W., Hoste I., Vanhecke L., Van den Bremt P., Vercruysse W. & De Beer D., Atlas van de flora van Vlaanderen en het Brussels gewest. Instituut voor Natuur- en Bosonderzoek, Nationale Plantentuin van België en Flo.Wer: 708.
Werner P.A. & Soule J.D. (1976) The biology of Canadian weeds: 18. Potentilla recta L., P. norvegica L., and P. argentea L. Canad. J. Plant Sci. 56(3): 591-603. [available online at: http://pubs.aic.ca/doi/pdf/10.4141/cjps76-095]