Ranunculus aquatilis aka Common Water Crowfoot

Ranunculus aquatilis is also known as common water crowfoot. It belongs to the buttercup family, Ranunculaceae. It is native to Europe and northwestern Africa. Its native range includes Britain and Ireland. It grows in temperate regions and lives in fresh water. In lowland Britain, it grows in ponds, ditches and streams. Other names are water buttercup, lodewort and water snowcups.

This short-lived perennial lives for more than one year. It forms mats, with growth both afloat and beneath water. It keeps its leaves through the year. Thin stems branch under water and bear finely cut leaves. Their narrow parts look like threads. The dark green floating leaves are palmately lobed. Their lobes spread like fingers from a hand. The two leaf forms give the plant different textures. Garden plants reach about 0.33 feet [0.1 m] tall. Their spread ranges from 0.33–1.64 feet [0.1–0.5 m]. They reach full size within one to two years.

Single white flowers bloom in summer. Each is about 0.07 feet [0.02 m] across. They sit above the finely cut growth beneath the water. The RHS suggests this species for gardens that support wildlife. It also suggests it for planting that needs little care. It lists ponds and bog gardens as places to grow it. Its low mats suit the edges of pools. The floating leaves and summer blooms add interest there.

Grow it in full sun, rooted in muddy pond edges. The recommended water depth is 0.49–1.97 feet [0.15–0.6 m]. It grows in fresh water with slow or fast flow. Clay, loam and sand all suit its roots. It grows in acidic, neutral and alkaline conditions. Both open and sheltered sites can suit it. The RHS gives it a hardiness rating of H7. This covers very cold conditions in Europe. Plants For A Future lists USDA zones 4–8. Sow seeds when ripe to raise new plants. Cut back the growth once the blooms have faded.

Pests cause few problems, but fungal diseases can occur. These include powdery mildew, rust and grey mould. Fresh parts are poisonous, and the sap can blister skin. The RHS warns of harm to both people and pets. Wear gloves and clothes that protect you when handling it. Plants For A Future records past food use of boiled plants. It also states that heat or drying breaks down the toxins. This does not mean the fresh plant is safe to eat. Its food rating is low, so take care.