This vegetation type is dominated by submerged mosses of the family Amblystegiaceae, especially Pseudo-calliergon trifarium. Scorpidium cossonii and S. scorpioides, combined with Utricularia minor, and rarely also U. intermedia. It occurs in shallow hollows with mesotrophic to oligotrophic and calcium-rich water in fens and other peatlands, and in the course of succession it develops towards minerotrophic mires. In the Czech Republic it occurs rarely in precipitation-rich basins and montane areas that are rich in mires.