There are 40 to 50 species with flowers that look like Nymphaea or water lilies.
Mostly perennial they are aquatic plants that grow on or in the water.
Stems, growing from rhizomes can be branched or unbranched.

The leaves are alternately arranged but may be opposite near the top of the stem.
Along the stem there are 1 to 3 leaves at each node.
Petioles, from 1 to 10 cm long have a base that sheaths the stem.
The floating blades are from 1.5 to 18 cm across.
They are heart-shaped to widely ovate or round with a smooth edge and faint palmate veins.
They can be smooth on both sides or have dense glands on the lower surface.
Some leaves may be purple or a purplish-brown.

Inflorescences can be 2 to 10 flowers at each node along the stem or a cluster at the end of a stem.
Flowers can have no pedicel or one up to 7 cm long.
The 5 sepals are fused at the base with the lobes being longer or shorter than the tube.
Sepals are up to 1 cm long with lobes that can be elliptic or lanceolate and with a round or pointed tip.

The bases of the 5 petals are fused with the lobes being longer or shorter than the tube.
The corolla is up to 3 cm across.
The lobes are spreading (rotate corolla) or semi-erect (campanulate or bell-shaped).
They can be ovate to elliptic, wedge-shaped or obovate and they sometimes have a central keel.
The lobes may have dense long hairs on either surface and the edges may have wings or be fringed.
There may be a clump of hairs at the base of each petal.
Petals are white, sometimes with a yellow centre or all bright yellow.

The 5 stamens are inserted onto the corolla tube opposite the sepals.
The filaments, sometimes with hairs are 0 to 4 mm long with anthers 1 to 6 mm long.
The ovary, from 0.5 up to nearly 2 cm long has a style from 1 mm to 1 cm long.
The styles on a plant may be of different lengths.
The 2 stigma lobes can be triangular or nearly spherical.
There are 5 yellow nectaries around the base of the ovary.

The fruit are almost round to elliptic indehiscent capsules with a few seeds.
The sometimes flattened seeds are mostly 1 to 2 (5) mm long.
The surface can be smooth or patterned and some have a few to dense short hairs.