Arum Lilly ?

Arum Lilly ?

Observation - Arum Lilly ? - UK and Ireland. Description: Yellow lilly which appears to be Arum. I cannot find it in wild flowers. Is this an escaped cultivar? It is growing in fresh running water.

Yellow lilly which appears to be Arum. I cannot find it in wild flowers. Is this an escaped cultivar? It is growing in fresh running water.