Oenanthe aquatica

Oenanthe aquatica is a tuberous perennial herb. It has an erect posture, fern-like finely-dissected leaves and small white composite umbels of flowers. All parts of the plant are poisonous.[2][3] Plants are hermaphrodite and self-fertile.[4]

A close-up on flowers of Oenanthe aquatica, growing in Karlsruhe, Germany

It is native to Europe, found in wetlands, in still or slow-moving water, from Sweden in the north to Sicily in the south and from Ireland in the west to Russia in the east.[1] It has also been recorded in East Asia.[5]

It grows particularly well in bodies of water with deep eutrophic silt and where the water level is very variable, for example in shallow ponds and ditches, but is also found on lakes, reservoirs, canals, streams and rivers, in marshes and seasonally flooded depressions. It is limited to low altitudes and cannot tolerate saltwater.[6]

This species is pollinated by bees, flies and beetles.[7]

The species is considered 'least concern' and populations of Oenanthe aquatica are recorded as 'stable' by the IUCN.[8] In the United Kingdom, however, it is noted to have declined.[9]