Creeping spearwort

Ranunculus reptans, the creeping spearwort, is a small slender perennial herb in the family Ranunculaceae with a circumboreal distribution across northern Europe, northern Asia, and northern North America, where it grows on the gravelly, sandy, or muddy margins of upland lakes, oligotrophic ponds, and seasonally inundated shores. The plant produces extremely slender thread-like creeping stolons that root at every node and develop tufts of small leaves and individual flowers, forming a low loose mat lying flat on the ground or just below the water surface. Leaves are alternate, simple, linear to narrowly oblanceolate ("spear-shaped", giving the common name), 1-4 cm long and 1-3 mm wide, entire and glabrous, all tapering to a narrow petiolate base. Flowers are solitary, borne on slender erect peduncles 2-6 cm long arising from the leaf axils, each 6-10 mm across with five glossy bright-yellow obovate petals and five greenish-yellow sepals; the receptacle bears numerous yellow stamens and a small head of green carpels. Flowering occurs in summer (June-August). The fruit is a small spherical aggregate of plump glabrous achenes, each ovoid and tipped with a short straight beak. The species is treated by some authorities as a stoloniferous variety of Ranunculus flammula.