These outliers have a common fauna, which is closely related to that of the interior of the United States.
Above sea-level, at the foot of the Beshtau, Mashuk and three other outliers of the Caucasus range, which protect it on the north.
The great tropical family of the Gesneraceae has left behind a few outliers: Ramondia in the Pyrenees, Haberlea in the Balkans, and Jankaea in Thessaly; the Pyrenees also possess a minute Dioscorea, sole European survivor of the yams of the tropics.
Dipterocarpeae and Nepenthaceae only extend with a few outliers into the African sub-region.
Amongst Rubiaceae, Cinchoneae with some outliers in the Old World have their headquarters at cooler levels.