Wetlands where disturbance is limited, although levels of environmental stress may be high as in some upland examples. In large open-water bodies, it is confined to well-vegetated margins, but it is particularly characteristic of mires and seepages which may have little open water, but which remain permanently wet. Water level fluctuations are not usually significant or at least, when they do occur, the substrate rarely dries out completely. Consequently this assemblage type is dominant on wet peat. They have often been in longer existence than mineral marsh habitats.