Sparse formations of narrow-leaved floating pondweeds, in particular, Potamogeton polygonifolius (Potamogeton oblongus), Potamogeton gramineus, Potamogeton alpinus, with Callitriche spp., Ranunculus ololeucos, Ranunculus omiophyllus, Ranunculus tripartitus, Luronium natans, Sparganium minimum, Apium inundatum of shallow, oligotrophic, clean, fluctuating, but usually permanent, often small, waterbodies of the Palaearctic region. Communities of this unit often form in close proximity to those of unit C3.413 and evolve into them with regular or prolonged desiccation.