Crocus xstellaris Haw. (= C. angustifolius Weston x C. flavus Weston) (Hybr.) – A rare escape from cultivation or merely a throw-out or garden relic. Probably locally more or less established.
This hybrid probably is the most widespread yellow-flowered crocus in Belgium, in cultivation as well as in the wild (see also Stace 2010).
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.