Silene schafta S.G. Gmel. ex Hohen. (Caucasus) – A very rare escape from or relic of cultivation. Discovered in 2002 on xerophilous rocks in Sart Tilman (Liège), obviously introduced on purpose (along with Alyssum montanum and Dianthus subacaulis). Very persistent and now more or less naturalized. In 2012 and 2013 also recorded in urban habitats in Gent and Leuven.
Silene schafta is also cultivated as an ornamental in rock gardens. It rather easily escapes and might become established on old walls. As such, it has been recorded from Amsterdam, the Netherlands (where it was initially confused with Saponaria ocymoides in Denters 2004) and from Douai, France (brick quay of river Scarpe; pers. obs. F. Verloove).
Silene schafta superficially resembles Saponaria ocymoides. However, Silene schafta has three styles and a calyx with six teeth (respectively two and four in Saponaria ocymoides).
Selected literature:
Clement E.J. (2000) An update on Caryophyllaceae in Alien Plants. BSBI News 85 : 46-47.
Denters T. (2004) Stadsplanten. Veldgids voor de stad. Fontaine Uitgevers, ‘s-Graveland: 432 p.