Included here is northern Greece (including the Pindos Mountains), parts of Albania, Macedonia, Bosnia-Herzegovina, Croatia, Slovenia (including the Karawanken and Julian Alps), but not the Adriatic coastal areas of these states. Its northeastern boundary runs mostly along the valley of the River Sava and continues along the Danube River to include most of Bulgaria with the exception of its northeastern steppe regions. In the southeast it extends into European Turkey. Also included is the so-called Pannonic zone named after the old Roman province of Pannonia, which is a western enclave of the steppe region and centred on the Hungarian Plain but also includes southern Romania and northern Bulgaria. In fact, it forms a corridor of lowlands along either side of the Danube River on the northwestern coast of the Black Sea.
Of the endemic plants so far recorded there are 335 species in 160 genera and 52 families. There are four endemic genera (marked red) but no endemic families. However, an unusual feature is the presence of endemic, archaic members of the now largely tropical and subtropical family Gesneriaceae.
Polunin, O. 1980. Flowers of Greece and the Balkans. Oxford University Press.
Turrill, W. B. 1929. The Plant life of the Balkan Peninsula - a phytogeographical study. Oxford.
Webb, D. A. 1966. The Flora of European Turkey. Proceedings of the Royal Irish Academy, 6: 1-100.