Nuphar lutea

Nuphar lutea – Yellow Pond lily.

Family Nymphaeaceae.
The Nuphar genus has 9 to 15 species, many synonyms and a large number of hybrids.

N. lutea are perennial aquatic plants with thick rhizomes from which the leaves and
    flowers arise separately.

Leathery leaves, up to 35 cm long, are oval or heart-shaped.
They are flat and on, or above the water.
A notch runs from the leaf margin to the petiole attachment.
Pinnate venation.

The cup-shaped yellow flowers are solitary and held above the water.
They are only 2 to 4 cm across.

The calyx has 5-6 large, bright yellow petal-like sepals.
The corolla has over 5 small, yellowish petals largely hidden by the sepals and stamens.

There are many strap-like stamens plus staminodes.
The carpels are in a superior ovary.
The stigma disc is round or star-shaped.

The fruit is a large berry that splits into individual carpels containing numerous seeds.