It is not unusual to find water-lilies in ponds and more often than not they are white ones which have 'escaped' into the wild. The yellow water-lily (Nuphar lutea) however is different and not just because it is yellow! It is a native species and I think I am right in saying it is our only native water-lily. Secondly, it seems to be more often seen in slow moving rivers rather than in ponds and all of my observations have been from the River Stour in Dorset. Then, the flower heads are on stalks rather than resting on the water surface; this reduces the resistance to the moving water and so protects the flower. The petals on white water-lilies tend to open out forming a star but on the yellow lily the curve upwards cupping the central stamens and style
The plant apparently has a faint smell of brandy and with the upturned petals making a cup shaped this flowers is nicknamed the brandy glass.