Plants glabrous or sometimes hirsute. Stems creeping (erect in Ranunculus sceleratus), not bulbous-based, without bulbils. Roots basal and usually also nodal, never tuberous. Leaves all cauline or both basal and cauline; basal and lower cauline leaves similar, petiolate, blades lobed to divided or (submerged leaves) deeply dissected, segments undivided or lobed. Inflorescences 2-25-flowered cymes or axillary solitary flowers. Flowers pedicellate; sepals deciduous soon after anthesis, 3-5; petals 3-14, yellow; nectary scale variable, forming crescent-shaped ridge surrounding but not covering nectary, or funnel-shaped tube surrounding nectary, or distal margin of funnel expanded to form large flap, then nectary sometimes displaced onto flap, glabrous, free margin entire; style present or absent. Fruits achenes, 1-locular; achene body thick-lenticular or compressed-ellipsoid to discoid, 1.2-3 times as wide as thick, not prolonged beyond seed; achene wall thick, smooth or with weak transverse wrinkles, glabrous; margin a thick, low or high corky band or ridge; beak much shorter than achene body or sometimes absent.

Distribution

Widespread, in marshy or aquatic habitats.

Discussion

Species ca. 15 (4 in the flora).

Selected References

None.

Lower Taxa

Ranunculus flabellaris, Ranunculus gmelinii, Ranunculus hyperboreus, Ranunculus sceleratus

Key

1	Stems erect, rooting only at base (very rarely also at proximal nodes).	Ranunculus sceleratus
1	Stems prostrate and rooting at nodes, or floating and rootless.	> 2
2	Leaf blades 0.3–1.2 cm, deeply 3-lobed or -parted, terminal segment entire or distally crenulate; nectary-scale low crescent-shaped ridge surrounding nectary; style 0.1–0.2 mm.	Ranunculus hyperboreus
2	Leaf blades 0.6–7.3 cm, 3-parted, terminal segment again lobed or dissected; nectary-scale a free flap, nectary on surface of flap; style 0.2–1.2 mm.	> 3
3	Styles 0.2–0.4 mm in flower; achenes 1–1.6 mm, beaks 0.4–0.8 mm; petals 3–7 mm	Ranunculus gmelinii
3	Styles 0.8–1.2 mm in flower; achenes 1.8–2.2 mm, beaks 1–1.8 mm; petals 7–12 mm.	Ranunculus flabellaris