Iris x hollandica Hort. (?? I. tingitana Boiss. & Reut. × I. xiphium L. or I. filifolia Boiss. × I. tingitana??) (Cult.) – An exceptional and probably ephemeral escape from cultivation or a mere throw-out. A single individual was found on a grassy canal bank in Izegem in 2017.
This hybrid belongs to subgenus Xiphium (Mill.) Spach. Species from this group combine channeled leaves and the presence of bulbs, features that are not encountered in the other members of Iris currently found in Belgium. Although relatively frequent in cultivation, this taxon has rarely been recorded in the wild. Stace (2010) provides details for the British Isles. See also Clement & Foster (1994).
Two closely related species – both putative parents – have also been recorded in the British Isles, I. xiphium and I. latifolia (Mill.) Voss (Stace 2010). Both differ from I. xhollandica in having shorter perianth tubes (less than 10 mm long) and flowers that are predominantly bluish-violet (more often yellow and white in I. xhollandica).
Selected references
Clement E.J. & Foster M.C. (1994) Alien plants of the British Isles. BSBI, London: XVIII + 590 p.
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.