Stream water-crowfoot

Ranunculus penicillatus, the stream water-crowfoot, is a perennial aquatic herb of the family Ranunculaceae that grows submerged in flowing rivers, streams, and ditches across Europe, Morocco, and parts of western Asia. The slender, flexible stems trail in the current, often forming long, ribbon-like underwater swards, and bear two distinct leaf forms: finely dissected, thread-like submerged leaves that fan out in the water, and (sometimes) rounded, shallowly lobed floating leaves. White flowers 1-2 cm across, each with five petals bearing a yellow basal nectar pit, are held just above the water surface on emergent peduncles in late spring and early summer. The species is taxonomically complex, with several subspecies and frequent hybridisation, and serves as an important indicator of clean, well-oxygenated lotic habitats.