In total, 21 calcifugous grasslands and montane communities have been identified.
The calcifugous grasslands and montane communities consist of the following groupings:
five grass-dominated communities which group together as "sub-montane calcifugous grasslands"; two of these, U1 and U2 are found throughout Britain, two more U4 and U5 are found throughout upland areas of Scotland, Wales and northern and western England, and one, U3, is localised in southwest England.
a sixth submontane community, U6, dominated by Heath Rush Juncus squarrosus
four communities categorised as "calcifugous vegetation of low- and middle-alpine snow-fields", all of which are confined or nearly confined to Scotland: U7, U8, U11 and U12
two moss- and rush-heaths of low- and middle-alpine plateaus U10, which is confined to Scotland, and U9 which is also found in northern England and North Wales
five communities grouped together as "mesotrophic montane swards and herb-rich banks and ledges": U13, U14, U15, U16 and U17; some of these are confined to Scotland while others extend into northern England or North Wales
four calcifuge fern communities, one of which, U20, is widespread; the remaining three (U18, U19 and U21) are confined to upland areas of northern and western Britain
List of calcifugous grasslands and montane communities