Trifolium squamosum L. (syn.: T. maritimum Huds.) (S and W-Eur., N-Afr., W-As.) – A very rare and ephemeral alien. In the 19th century frequently seen in coastal habitats (at least since 1854) and often considered to be native (Durand 1899, Lawalrée 1961). This is now difficult to assess but most records were from atypical and often disturbed habitats (old walls, road verges, ruderalized dunes, etc.). In its native area Trifolium squamosum preferably grows in brackish meadows, near tidal rivers and by creeks (Sell & Murrell 2009). In Belgium it was formerly collected along river IJzer near Nieuwpoort between 1854 and 1891 and this might have been a spontaneous (but rather disjunct) occurrence. Yet it is absent in natural habitats in adjacent parts of northwestern France. It seems more likely that Trifolium squamosum was formerly more or less widely naturalized along the Belgian coast. It has been recorded at various points from De Panne to Knokke (Blankenberge, Knokke, Koksijde, Middelkerke, Nieuwpoort, around Oostende and Zeebrugge). It was last seen in 1923 and 1951 on waste land in Oostende (doubtlessly introduced). Exceptionally seen elsewhere, for instance in a clover field in Herent in 1877. In 1995 seen in quantity on a demolition site of a former horse artillery in Gent (from a long-buried seed bank; see Verloove & Heyneman 2012).
Selected literature:
Durand T. (1899) Phanérogames. In: De Wildeman E. & Durand T., Prodrome de la flore belge. A. Castaigne Editeur, Bruxelles: 1112 p.
Lawalrée A (1961) Papilionaceae. In: Robyns W. (ed.), Flore Générale de Belgique, vol. 4, fasc. 1. Jardin Botanique de l’Etat, Bruxelles: 9-134.
Sell P. & Murrell G. (2009) Flora of Great Britain and Ireland. Vol. 3 Mimosaceae – Lentibulariaceae. Cambridge University Press, Cambridge: XXVIII + 595 p.
Verloove F. & Heyneman G. (2012) Merkwaardige plantencollecties van twee antropogene zaadbanken in Gent (Oost-Vlaanderen, België). Dumortiera 100: 19-24. [available online at: http://www.br.fgov.be/DUMORTIERA/DUM_100/Dum%20100_19-24_Zaadbanken%20Gent-Verloove%20en%20Heyneman.pdf]