Menyanthes

Bog bean is an aquatic perennial found across the Northern Hemisphere, including most of the UK. Its a monotypic genus (only one species), but a closely related genus, Nymphoides peltata, the fringed water-lily, is in the same family (Menyanthaceae), has similar 'fringed' or 'feathery' flowers. According to some research this a device to deter ants!