This association is dominated by Callitriche hamulata, which usually occurs in a submerged growth form, but in places with exposed bottoms it can also occur in a terrestrial growth form. Habitats include brooks, channels, upper and middle river courses, and less frequently also small fishponds, fish storage ponds and oxbows. Water is cool and oligotrophic to mesotrophic, in places even dystrophic. Bottom is usually sandy to clayey. This vegetation type is common in cool submontane areas of the Czech Republic, but it is poorly documented.