1. Aurinia saxatilis (L.) Desv. (syn.: Alyssum saxatile L.) (C and SE-Eur.) – A very rare, locally naturalized escape from cultivation. Apparently first recorded on an old wall in Diest in 1889. Furthermore seen on a dump in Jamioulx in 1953 (ephemeral). More recently obviously increasing. Seen, for instance, (mostly on old walls) in Bellefontaine, Brussel, Colfontaine, Dour, Gemmenich, Goegnies-Chaussée, Guirsch, Heusden, Leuven, Mechelen, etc. In several localities Aurinia saxatilis appears to be perfectly naturalized. Also reported from old walls in Houx by Duvigneaud (1988). Surely overlooked or neglected elsewhere, especially in Wallonia.
Aurinia saxatilis always grows on dry, sun-exposed, usually calcareous substrates (so far always in artificial habitats).
The infraspecific variability of Aurinia saxatilis in Belgium has not been studied so far. Several different subspecies were distinguished by Persson (1971).
Duvigneaud J. (1988) La réserve naturelle domaniale de Poilvache à Houx (Yvoir). Mise en évidence de sa vocation didactique. Nat. Mosana 41(4): 113-136.
Küpfer P. & Nieto Feliner G. (1993) Alyssum bilimekii Willk. = Aurinia saxatilis (L.) Desv. (Cruciferae). An. Jard. Bot. Madrid 51(1): 169-170.
Persson J. (1971) Studies in the Aegean: 19. Notes on Alyssum and some other genera of Cruciferae. Bot. Notiser 124(3): 399-418.