- Name also: Spatterdock, Cow Lily, Yellow Pond-lily, Brandy-bottle
- Family: Water-lily Family – Nymphaeaceae
- Growing form: Perennial herb. Aquatic plant, with floating leaves and thick creeping rhizome.
- Height: 0.5–3 m (1.5–10 ft.)
- Flower: Regular, yellow, 4–6 cm (1.6–2.4 in.) across. The 4–6 yellowish-green sepals are much longer than the petals. Petals 15–20, yellow. Stamens numerous. Stigma shield-like, concave.
- Leaves: Blade of the floating leaves broadly elliptic to oval, light green, stalk angled, up to 40 cm (16 in.) long. Submerged leaves roundish and wrinkled.
- Fruit: Flask-shaped, 4–6 cm (1.6–2.5 in.) long, full of seeds dividing irregularly into many segments.
- Habitats: Lakes, ponds, rivers, streams, bays of brackish water.
- Flowering time: June–August.
Water-lilies (Nymphaea spp. and Nuphar spp.) are among the most primitive dicotyledons. Features such as the spiral arrangement and great numbers of floral leaves are considered to be signs of this. On the other hand, the floating leaves represent a high level of specialisation.
Yellow water-lilies are perennials with strong rootstocks and both submerged and floating leaves. When not flowering, yellow water-lilies can be distinguished from white water-lilies (Nymphaea) by the leaf venation. The leaf veins of yellow water-liliy species end at the blade margin and do not form a net-like pattern like those of white water-lily species.