Euphorbia myrsinites L. (Medit., Caucasus) – A very rare, more or less persistent escape from cultivation or garden throw-out. Known from an off-ramp near Beaumont around 1968. Apparently self-sowing and spreading (Lebeau 1968) but probably extinct now. Recently also observed on dry, gravelly soil between Zutendaal and Munsterbilzen near the Albertkanaal (a small population discovered in 2007 but partly destroyed soon afterwards; few specimens still present in 2009). More recent records are available from Eksel, Geel, Koksijde and Mol-Balen.
Euphorbia myrsinites is increasingly cultivated in rock gardens or for ground cover in Belgium and seems to reproduce rather easily where-ever grown. More records surely will come to light but a wider, genuine naturalization seems rather unlikely (the number of suitable habitats probably being restricted).
Selected literature:
Brennenstuhl G. (2012) Verwilderungen von Euphorbia myrsinites im Altmarkkreis Salzwedel (Sachsen-Anhalt). Florist. Rundbr. 45-46: 32-36.
Clement E.J. (2000) Euphorbia myrsinites established in Cambs. (v.c. 29). BSBI News 85: 39.
Lebeau J. (1968) Excursions dans les marais de Bomerée en 1968. Nat. Mosana 21(4): 153-156.
Pahlevani A.H., Geltman D.V. & Riina R. (2011). Taxonomic revision of Euphorbia subsection Myrsiniteae Boiss. for the flora of Iran. Ann. Bot. Fennici 48: 483-493. [available online at: http://www.academia.edu/2125670/Taxonomic_revision_of_Euphorbia_subsect._Myrsiniteae_in_Iran]