How are the wild celery species in Germany?

The wild celery species in Germany are Apium graveolens (wild celery), Helosciadium inundatum, H. nodiflorum and H. repens. All in all, the four wild celery species in Germany are endangered, as there are only rather small and too few populations.
The species occur in moist to wet habitats, are in need of light and weak in competition. The occurrences usually only exist because natural disturbances (e.g. beaten paths of wild animals) or e.g. grazing pushes back the more competitive species. In many wild celery populations, however, such effects are not sufficient, so that the populations remain very small and could even go extinct. Presence checks in 2015 confirmed a large number of known occurrences. This did not apply to H. inundatum, which occurs predominantly in small ponds in northwestern Germany. This species could only be found in about half of the original habitats. One possible reason for this is that small waters sometimes overgrow because they are no longer maintained and accumulate nutrients.