Crepis sancta (L.) Bornm. (syn.: Lagoseris sancta (L.) K. Malý, Pterotheca sancta (L.) C. Koch) (SE-Eur., SW-As.) – A rare and much decreasing, usually ephemeral alien. First recorded in 1948 in Lasne-Chapelle along a tramline. Subsequently in Kinkempois in 1951 (railway yard) and suddenly much expanding for some time in the 1950’s (Charleroi, Farciennes, Ghlin, Obourg, Oudergem, Tervuren, Thimister, Zottegem, etc.; see Lawalrée 1954). Near Oudergem apparently more or less established between 1956 and 1965. Most records were made near railway tracks, in road verges or on coalmine heaps. From the 1960’s onwards much decreasing: observed in 1960 in Chimay and in 1971 in Annevoie. The most recent records date back to 1996 when Crepis sancta was observed in two quarries near Thon (Andenne; it was no longer seen there in 2005) and to 2016 when few plants were found on gravel in a railway yard in Boom.
Alien populations in western Europe are ascribed to subsp. nemausensis (Vill.) Babc. (syn.: Lagoseris nemausensis (Gouan) C. Koch), a more western subspecies but of questionable taxonomic value (and no longer upheld by modern taxonomists).
Crepis sancta somehow resembles native Hypochaeris radicata in general habit but it is annual.
Hidayati S.N. (2001) Inbreeding depression under intraspecific competition in a highly outcrossing population of Crepis sancta (Asteraceae): evidence for frequency-dependent variation. Amer. J. Bot. 88: 1424-1429.
Imbert E. (1999) The effects of achene dimorphism on the dispersal in time and space in Crepis sancta (Asteraceae). Canad. J. Bot. 77(4): 508-513.
Imbert E. (2002) Historique de Crepis santa (L.) Babc. dans la flore francaise. J. Bot. Soc. Bot. France 16: 33-39.
Lawalrée A. (1950) Notice sur des phanérogames adventices en Belgique. Bull. Soc. Roy. Bot. Belg. 83: 43-49.
Lawalrée A. (1954) L’expansion de Crepis sancta (L.) Babc. subsp. nemausensis (Gouan) Babc. Bull. Soc. Roy. Bot. Belg. 87: 203-205.