Ranunculus repens is an herbaceous perennial that usually creeps along the ground. Nonflowering, arching, creeping stems form roots at the nodes. The plant is usually hirsute, though it can be glabrate.
Foliage
Leaves are 3-parted; terminal division is stalked; divisions are broadly ovate to subrotund; also cleft or lobed; often having sharp teeth along the margins; apex of leaves is obtuse to acuminate; leaves measure 0.4-3.3 in. (1-8.5 cm) long and 0.6-4 in. (1.5-10 cm) wide; petioles are long and pubescent, measuring 0.5-10 in. (1.25-25 cm).
Flowers
Flowers are bright yellow and appear in May to July. They are about 1 in. (2.5 cm) across and have 5-7 obovate petals that exceed the spreading sepals. Each of the petals measures 0.3-0.6 in. (8-15 mm) in length. The receptacle of the flower is usually hispid, but may rarely be glabrous.
Fruit
Fruits are spherical achenes that measure 0.1 in. (2.5-3.5 mm) in diameter. These achenes have sharp, narrow margins and are tipped with a short, curved beak.
Ecological Threat
It can form large monocultures that crowd out native plants, especially in coastal headlands. It is often mistaken for native buttercups. Ranunculus repens occurs most commonly in rich, damp soil, but can be found in moist sand or gravel.