Erinus alpinus L. (mountains of SW and SC Eur.) – A very rare, locally naturalized escape from cultivation. Apparently first recorded on old walls in Thuin in 2008. Subsequently also collected in Huy (2010) and Oostende (2017). Additional recent records are available from Givry and Jurbise (comm. P. Dupriez 2012). At least in Thuin Erinus alpinus looks perfectly naturalized.
Selected literature:
Brandes D. & Nitzsche J. (2013) Verwilderungen von kultivierten Arten im Freiland des Botanischen Gartens Braunschweig. Braunschweiger Geobotanische Arbeiten 10: 1-27.
Crafter W. (1966) Erinus alpinus in the wild. N. Gardener 20: 130-132.
Higgins R. (1990) Fairy foxglove and the Romans. Plant-Lore Notes & News 14: 62.
Jury D.W., Rob C.M. & Rae A.G. (1966) Erinus alpinus in the wild. N. Gardener 20: 204-205.
Steinwendtner R. (1972) Erinus alpinus L. neu fur Oberösterreich. Mitt. Bot. Arbeit. Oberösterr. Landesmus. Linz 4(1-2): 45.