Cuscuta gronovii Willd. ex Schult. (syn.: Grammica gronovii (Willd. ex Schult.) Hadac et Chrtek) (N-Am.) – A very rare and apparently ephemeral alien. Recorded between 1950 and 1956 on ornamental plants (Aster, Solidago) in the botanical garden of Brussel and in 1954 in Leopoldsburg as a parasite of Beta vulgaris. The records from the botanical garden correspond well with the results of a recent study by Galera & al. (2010).
Cuscuta gronovii is locally naturalised in riparian habitats in neighbouring territories, for instance in France, Luxemburg (Lambinon & al. 2004), Germany (Duvigneaud 1978) and the Netherlands (van der Meijden 2005). However, it seems to have decreased considerably in recent times. It is more widely dispersed in Central Europe.
All European populations have been ascribed to var. calyptrata Engelm. which is rather surprising since it has a narrowly restricted native distribution range (Costea & al. 2006). Hence, its infraspecific variability probably requires further study in Europe.
Selected literature
Duvigneaud J. (1978) Les cuscutes de la vallée de la Moselle (Cuscuta europaea, C. gronovii var. calyptrata et C. lupuliformis). Nat. Mosana 31: 22-27.
Costea M., Nesom G.L. & Stefanovic S. (2006) Taxonomy of Cuscuta gronovii and Cuscuta umbrosa (Convolvulaceae). Sida 22(1): 197-207.
Costea M. & Tardif F.J. (2006) The biology of canadian weeds. 133. Cuscuta campestris Yuncker, C. gronovii Willd. ex Schult., C. umbrosa Beyr. ex Hook., C. epithymum (L.) L. and C. epilinum Weihe. Can. J. pl. Sci. 86: 293-316.
Galera H. & Sudnik-Wojcikowska B. (2010) Central European botanic gardens as centres of dispersal of alien plants. Acta Societ. Botan. Polon. 79(2): 147-156.
Jilek B. (1974) Uber das Vorkommen der Art Cuscuta gronovii Willd. in Südbohmen. Novit. Inst. Bot. Univ. Agron. Prag. 1: 3-10.
Lambinon J., Delvosalle L., Duvigneaud J. (avec coll. Geerinck D., Lebeau J., Schumacker R. & Vannerom H. (2004) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Cinquième édition. Jardin botanique national de Belgique, Meise: CXXX + 1167 p.
Van der Meijden R. (2005) Heukels’ Flora van Nederland (23e druk). Wolters-Noordhoff, Groningen: 685 p.