What are the main floristic patterns in the Pannonian and western Pontic steppe grasslands? What are the diagnostic species of the major subdivisions of the class (temperate Euro-Siberian dry and semi-dry grasslands)?Carpathian Basin (E Austria, SE Czech Republic, Slovakia, Hungary, Romania, Slovenia, N Croatia and N Serbia), Ukraine, S Poland and the Bryansk region of W Russia.We applied a geographically stratified resampling to a large set of relevés containing at least one indicator species of steppe grasslands. The resulting data set of 17 993 relevés was classified using the TWINSPAN algorithm. We identified groups of clusters that corresponded to the class . After excluding relevés not belonging to our target class, we applied a consensus of three fidelity measures, also taking into account external knowledge, to establish the diagnostic species of the orders of the class. The original TWINSPAN divisions were revised on the basis of these diagnostic species.The TWINSPAN classification revealed soil moisture as the most important environmental factor. Eight out of 16 TWINSPAN groups corresponded to . A total of 80, 32 and 58 species were accepted as diagnostic for the orders , and , respectively. In the further subdivision of the orders, soil conditions, geographic distribution and altitude could be identified as factors driving the major floristic patterns.We propose the following classification of the in our study area: (1) (semi-dry grasslands) with (steppe meadows of the forest zone of E Europe) and (meadow steppes on deep soils in the forest-steppe zone of E Central and E Europe); (2) (grass steppes) with (grass steppes on less developed soils in the forest-steppe zone of E Central and E Europe) and (grass steppes in the steppe zone); (3) (rocky steppes) with (rocky steppes on siliceous and intermediate soils), (thermophilous rocky steppes on calcareous soils), (dealpine grasslands of the Western Carpathians) and (dealpine grasslands of the Romanian Carpathians).