Cali, Polunin also writes that the origine of I. germanica is unknown, but that it is naturalized in waste places. In Flowers of Greece, (Lafranchis & Sfikas), it is written that there are 11 native Iris species in Greece, and I.germanica is among the listed 11, but also that both this and the bluish-white var. florentina are found all over Greece and they are widely cultivated, the same for the pure white I. albicans.
Several years ago I found lots of them in a ditch between a field and the road in Halkidiki, both blue and white ones, the next year they were all gone and I haven’t seen them since.