Salvinia natans (L.) All. (Eur., temp. As., N-Afr.) – Formerly very persisting or locally naturalised (Lanaken 1862-1878, Willebroek 1889) and sometimes even claimed as native (Lawalrée 1964). More recent records proved to be referable to Salvinia auriculata.
Perhaps no longer cultivated and rather unlikely to re-occur.
Selected literature
Gałka A. & Szmeja J. (2012) Distribution, abundance and environmental conditions of the clonal aquatic fern Salvinia natans (L.) All. in the Vistula Delta (Baltic Sea Region). Biodiv. Res. Conserv. 28 (DOI: 10.2478/v10119-012-0020-7).
Lawalrée A (1950) Ptéridophytes. In: Robyns W. (ed.), Flore Générale de Belgique, vol. 1. Jardin Botanique de l’Etat, Bruxelles: IV + 194 p.
Lawalrée A (1964) Salvinia. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 1. Cambridge University Press, Cambridge: 24.