Ranunculus hederaceus

Lore & Background

The species was named by Linnaeus in 1753 in Species Plantarum. The generic name Ranunculus is Late Latin for 'little frog', while the specific epithet hederaceus means 'like ivy', referring to the leaf shape. Common names include the Welsh Crafanc-y-Frân Dail Eiddew ('ivy-leaved claw') and the Swedish Murgönsmöja ('ivy flower').

Ivy-leaved crowfoot is a small, creeping plant with stems up to about 50 cm long. Its leaves are dark blueish-green on the upper surface and paler below, 2.5–3.5 cm across, with 3–5 shallow lobes broadest at the base. The flowers are solitary on 1–2 cm pedicels, with 5 narrow white petals about 3 mm long, each with a yellow base and a crescent-shaped nectar pit; the petals do not touch or overlap. There are 5 green sepals almost as long as the petals, and the flowers are bisexual with 9–43 carpels on a hairy receptacle and numerous bright yellow stamens. The fruits are hairless, about 2 mm long, sometimes with a narrow wing.

It is distinguished from other water crowfoots by the absence of submerged capillary leaves and by its shiny, ivy-shaped leaves with 3–5 shallow lobes, broadest at the base and sometimes darker in the centre. It grows in mineral waters, whereas the similar round-leaved crowfoot is 'invariably' found in more peaty waters.

Reader's Guide

Ivy-leaved crowfoot is commonly associated with bare muddy ground close to water, carpeting shallow water and drainage ditches. It often grows on cattle-poached edges of ponds, ditches and streams, in wet gateways and on paths and tracks, and sometimes disappears for a year or two in dry times. The species appears characteristic of contact zones between elevated oligotrophic sandy soils and eutrophic or polluted small streams or artificial running waters, or of stagnant waters strongly influenced by seepage phenomena. Its Ellenberg values in Britain (L = 7, F = 9, R = 5, N = 5, S = 0) indicate it favours wet, sunny places with neutral to slightly acid soil and low fertility, avoiding brackish situations. In the British National Vegetation Classification it is associated with two aquatic communities: A13 alternate-leaved water-milfoil vegetation (typical of low-nutrient waterbodies towards the north and west) and A8 yellow water-lily community (typical of rivers, ditches and canals in the lowlands in the south). It is more common in water margin vegetation than open water, and has been found in OV30 trifid bur-marigold, OV32 lesser spearwort and OV35 blinks communities. The UK is thought to hold at least 20% of the global population. Known to cause gastrointestinal distress, but also sometimes used to treat skin conditions and wounds.

Did You Know?

• The specific epithet hederaceus means 'like ivy', from the shape of the leaves.
• It has no submerged capillary leaves, unlike most other water crowfoots.
• The flowers have 5 narrow white petals with a yellow base and a crescent-shaped nectar pit.