Eryngium planum L. (SE-Eur.) – A rare and usually ephemeral escape from cultivation. Apparently first collected around 1850 in the surroundings of Mons. Furthermore recorded in Sint-Job-in-‘t-Goor (1942), Laken (1946), Deurne (1951), Antwerpen (1956), Hamont (1967), Roeselare (1998), Melle (2003) and Lissewege (2006). In 2010 also recorded in Kachtem and Zelzate. Since then rather regularly observed but usually in small number and not persisting (see here for an overview of recent records: http://waarnemingen.be/soort/view/20400). Many records are from road verges (more rarely also found on dumps, levelled soil, etc.). There was a remarkable concentration of records from coastal dunes and Eryngium planum might have been locally naturalized there for some time: reported to be naturalized in dunes in Raverszijde around 1922 and repeatedly recorded in sea dunes in Koksijde, at least between 1952 and 1970 (although it is not sure if all records are associated with one another). Finally, also observed in coastal dunes in Wenduine in 1985.
Selected literature:
Hiller K. (1971) Chemosystematics of the Saniculoideae. Bot. J. Linn. Soc. 64 Suppl. 1. 369-384.