Overview
Ranunculus acris is a fibrous-rooted herbaceous perennial in the Ranunculaceae family, growing 12–36 inches (30–90 cm) tall with an upright, branching habit. Basal leaves are palmately divided into 3–7 deeply lobed segments, each further incised, 2–4 inches (5–10 cm) across on long petioles; stem leaves are smaller and sessile. Stems are hollow, branching above mid-height, covered in fine appressed hairs. Flowers are glossy, bright yellow, 0.75–1 inch (2–2.5 cm) across with five rounded petals that have a distinctive waxy sheen caused by a specialised epidermal layer that reflects light in two planes simultaneously. Each petal has a nectary at its base covered by a small scale. Flowers are borne in open, branching cymes of 5–20+ blooms per stem. Fruit is a cluster of achenes, each 2–3 mm long with a short hooked beak. All parts contain the glycoside ranunculin, which converts to protoanemonin on tissue damage — a vesicant that causes contact dermatitis in humans and oral blistering in grazing livestock. Protoanemonin degrades to non-toxic anemonin when the plant is dried, making hay safe. Spreads by seed and by short rhizomes. In the Pacific Northwest, it is naturalised in pastures, meadows, roadsides, and disturbed ground, and is classified as a weed in agricultural settings. The double-flowered cultivar 'Flore Pleno' is grown ornamentally and does not set seed.
Native Range
Ranunculus acris is native across Europe, northern Asia, and into northwestern Africa. It has naturalised widely in North America, where it occurs in all 50 US states and all Canadian provinces, primarily in moist grasslands and disturbed ground.Suggested Uses
The species is used in wildflower meadow plantings and naturalised grassland, spaced 12 inches (30 cm) apart or broadcast-seeded at 1–2 g/m². The double cultivar 'Flore Pleno' is used in cottage garden borders — it does not set seed and has a longer bloom period. All forms tolerate seasonally wet soil and are suited to rain garden edges and pond margins.How to Identify
Appearance
Size & Dimensions
Height1' - 3'
Width/Spread1' - 1'6"
Reaches mature size in approximately 2 years
Bloom Information
Flowering occurs from May through July in the Pacific Northwest, with peak bloom in June. Individual flowers last 5–8 days. The branching cyme produces flowers sequentially over a 4–6 week period. Pollinated by a wide range of insects including bees, flies, and beetles attracted to the nectar and pollen.Detailed Descriptions
Foliage Description
Medium greenGrowing Conditions
Sun Requirements
Requires 4-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Plant in full sun to partial shade in moist, moderately fertile soil with a pH of 5.5–7.0. Space 12 inches (30 cm) apart. Tolerates a wide range of soil types including heavy clay, provided moisture is adequate during the growing season. In garden settings, grow the double-flowered 'Flore Pleno' to prevent self-seeding. Water during prolonged dry spells — foliage may go partially dormant in summer drought but recovers with autumn moisture. Feed lightly with a balanced fertiliser in early spring. Handle with gloves — the sap causes contact dermatitis in sensitive individuals.Pruning
Cut back flowering stems after bloom to prevent self-seeding and maintain a tidy basal rosette. In meadow plantings, delay cutting until seed has dispersed (July) if naturalisation is desired. Remove dead foliage in late autumn or early spring before new growth emerges.Pruning Schedule
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summer