Caltha natans is a species of flowering plant in the buttercup family.

Unlike other species of Caltha that are found in North America, C. natans shows relatively little morphological variation, and has not been divided into infraspecific taxa. The plants typically grow in shallow water, with floating leaves up to 25 millimetres (0.98 in) wide and 50 mm (2.0 in) long, on a petiole (leaf stalk) up to 70 mm (2.8 in) long. The flowers are roughly 5 mm (0.20 in) in diameter and have five white sepals; they are produced in late spring (June–August). Each flower forms 20–55 follicles, which contain black, elliptic seeds 0.5–0.8 mm (0.020–0.031 in) in diameter.