This species-poor vegetation type is dominated by Batrachium fluitans, or less frequently by B. penicillatum. Both species form tussocks of long stems with submerged leaves in running water. Some other species of running water may also occur, such as the aquatic moss Fontinalis antipyretica. They occur in the upper and middle reaches of streams, including some artificial channels, with fast-running, cool, clear and nutrient-poor water 10–60(–100) cm deep. The habitats are well insolated and have stony or gravelly bottoms. This vegetation type has scattered occurrences especially at the middle altitudes of the Bohemian Massif.