Thlaspietea rotundifolii is a class of vegetation developed on unstable, mobile screes formed of small to mid-sized rock fragments. In our concept, we exclude from this class vegetation on stabilized screes and talus slopes, which is floristically more closely related to the rock-outcrop vegetation of the Asplenietea trichomanis. Plants of mobile screes are exposed to a combination of disturbance due to scree movement and stress due to limited availability of water and nutrients. There are also large temperature differences, both temporal (between night and day or winter and summer) and spatial (between daytime-warm upper scree surface and its constantly cool interior part). In the Alps, Carpathians and many areas of southern Europe there are large areas of screes which have continuously supported non-forest vegetation throughout the Holocene. These screes harbour many scree-specialist species, several of them with relict or endemic status. Very few such historically continuous habitats occur in the Czech Republic, where scree vegetation mostly occurs in anthropogenic habitats such as quarries, and is poor in scree specialists.