This association is dominated by Bidens cernua. It occurs on the bottoms of summer-drained fishponds, fish storage ponds, oxbows, banks of small streams, ditches or channels. The substrate tends to be rich in nutrients, and is wet or flooded by shallow water. This type of vegetation can even occur in deep water, but it does not tolerate long-term substrate desiccation. In the Czech Republic it occurs mainly in colline areas across the country.