This association includes dense stands of Petasites hybridus, a perennial herb with large leaves. It occurs on river banks and alluviual sediments, on some sites even on gravelly deposits in the middle parts of stream channels; in these habitats it is the natural herbaceous vegetation of flood-disturbed sites. However, Petasites hybridus stands also develop in wet road ditches or in abandoned meadows. Soils contain a high proportion of sand or gravel and are rich in nutrients. In the Czech Republic this vegetation type is common in submontane and montane areas.