Plants glabrous or sometimes pilose or pubescent. Stems erect, not bulbous-based, without bulbils. Roots basal, sometimes tuberous. Leaves basal and cauline, simple or compound; basal leaves petiolate, blades variously divided, unlobed to deeply parted, compound, or filiform-dissected, segments undivided or again lobed or parted, margins entire or crenate, never serrate; cauline leaves sessile to nearly sessile or sometimes with much shorter petioles than basal leaves, blades lobed to compound or dissected (rarely unlobed in R. macauleyi and R. glaberrimus). Inflorescences 1-50-flowered cymes. Flowers pedicellate; sepals deciduous soon after anthesis, 5; petals yellow (rarely absent in R. pedatifidus); nectary scale joined with petal on 3 sides, forming pocket enclosing nectary (sometimes with apex free, forming flap shorter than pocket), glabrous or setose, free margin entire or fringed; style present. Fruits achenes, 1-locular; achene body thick-lenticular or asymmetrically thick-lenticular to compressed-globose, 1.2-2 times as wide as thick, not prolonged beyond seed; wall thick, smooth; margin low narrow ridge, often inconspicuous; beak much shorter than achene body.

Distribution

Worldwide except lowland tropics

Discussion

Species ca. 70 (22 in the flora).

Selected References

None.

Lower Taxa

Ranunculus abortivus, Ranunculus adoneus, Ranunculus allegheniensis, Ranunculus allenii, Ranunculus arizonicus, Ranunculus auricomus, Ranunculus cardiophyllus, Ranunculus eschscholtzii, Ranunculus gelidus, Ranunculus glaberrimus, Ranunculus harveyi, Ranunculus inamoenus, Ranunculus jovis, Ranunculus macauleyi, Ranunculus micranthus, Ranunculus nivalis, Ranunculus pedatifidus, Ranunculus pygmaeus, Ranunculus rhomboideus, Ranunculus sabinei, Ranunculus sulphureus, Ranunculus triternatus

Key

1	Abaxial surface of sepals with dense brown pubescence.	> 2
1	Abaxial surface of sepals glabrous or with colorless hairs.	> 4
2	Basal leaf blades narrowly elliptic to lanceolate or oblanceolate; s Rocky Mountains.	Ranunculus macauleyi
2	Basal leaf blades orbiculate to reniform; Canadian Rocky Mountains and Arctic.	> 3
3	Receptacle brown-pilose; basal leaf blades usually shallowly lobed, or unlobed with crenate margins.	Ranunculus sulphureus
3	Receptacle glabrous; basal leaf blades 3-parted.	Ranunculus nivalis
4	Basal leaves deciduous before anthesis; nectary scale ciliate, petals 2–3 times as long as wide.	Ranunculus arizonicus var. arizonicus
4	Basal leaves persistent; nectary scale glabrous, (glabrous or ± pilose in R. cardiophyllus and R. glaberrimus, which have petals 1–1.5 times as long as wide).	> 5
5	Some or all basal leaf blades unlobed.	> 6
5	All basal leaf blades lobed or parted.	> 14
6	Basal leaf margins entire or with 3 broad shallow rounded teeth; heads of achenes globose, 6–20mm wide.	Ranunculus glaberrimus
6	Basal leaf margins either crenate to crenate-lobulate, with more than 5 rounded teeth, or innermost teeth lobed or divided; heads of achenes usually ovoid to cylindric (sometimes globose and 3–8 mm wide).	> 7
7	Petals 1–3.5 mm.	> 8
7	Petals 4–18 mm.	> 10
8	Stems villous, sometimes sparsely so; receptacle glabrous; base of some roots ± swollen and tuberous, usually 1–2 mm thick; leaf base usually obtuse or truncate.	Ranunculus micranthus
8	Stems glabrous; receptacle pilose, sometimes sparsely so; base of roots never much swollen, 0.2–1.5 mm thick; leaf base ± cordate.	> 9
9	Sepals hispid; achene beak 0.6–1 mm.	Ranunculus allegheniensis
9	Sepals glabrous; achene beak 0.1–0.2 mm.	Ranunculus abortivus
10	Leaf blades wider than long; e of Great Plains, not in Great Lakes area.	> 11
10	Leaf blades at least as long as wide; Great Lakes area and Great Plains w to Great Basin.	> 12
11	Pedicels glabrous (see also R. escholtzii with lobed leaves); se United States.	Ranunculus harveyi var. harveyi
11	Pedicels pubescent, sometimes sparsely so; e Canada.	Ranunculus allenii
12	Sepals 5–8 × 3–7 mm; nectary scale ciliate, sometimes glabrous; leaf base cordate to broadly obtuse.	Ranunculus cardiophyllus
12	Sepals 3–6× 1.5–3mm; nectary scale glabrous; leaf base obtuse or acute to rounded.	> 13
13	Basal leaf blades ovate, obovate, or orbiculate; heads of achenes cylindric, 7–17 mm; achene beak 0.4–2 mm; Rocky Mountains, Great Basin, and Black Hills.	Ranunculus inamoenus
13	Basal leaf blades ovate to rhombic; heads of achenes depressed-globose, 4–6 mm; achene beak 0.2– 0.3 mm; n Great Plains and eastward.	Ranunculus rhomboideus
14	Basal leaf blades dissected into linear segments.	> 15
14	Basal leaves at most 1×-divided, segments not linear.	> 16
15	Roots slender, 0.8–1.4 mm thick; achene beak 1.2–1.7 mm.	Ranunculus adoneus
15	Roots 2–3 mm thick; achene beak 0.8–1.5 mm.	Ranunculus triternatus
16	Some roots clavate and tuberous, 2.5–5 mm thick; basal leaf blades deeply divided into 3 oblanceolate segments.	Ranunculus jovis
16	Roots not clavate or tuberous, 0.1–1.6 mm thick; leaves various but not as above.	> 17
17	Petals 7–15 mm.	> 18
17	Petals 1–8 mm.	> 20
18	Pedicels glabrous.	Ranunculus eschscholtzii
18	Pedicels pubescent.	> 19
19	Heads of achenes globose to short-ovoid; basal leaves 3-parted with segments again lobed or parted, margins toothed; Greenland.	Ranunculus auricomus
19	Heads of achenes cylindric; basal leaves pedately (5–)7(–9)-parted or -divided, segments sometimes again lobed, margins never toothed; throughout n North America.	Ranunculus pedatifidus var. affinis
20	Flowering stems 0.6–3.5 cm (sometimes longer in fruit); petals 1–3.5 mm.	Ranunculus pygmaeus
20	Flowering stems (1–)4–15(–27) cm; petals 3–8 mm.	> 21
21	Petals 6–16 mm; beak of achene straight, 0.6–1.8 mm; pedicels glabrous.	Ranunculus eschscholtzii
21	Petals 4–8 mm; beak of achene straight or curved, 0.3–0.7 mm; pedicels glabrous or pilose.	> 22
22	Base of basal leaves obtuse; petals 5–8 mm; arctic Alaska, Canada, and Greenland.	Ranunculus sabinei
22	Base of basal leaves nearly cordate to truncate; petals 4–5 mm; Alaska, Yukon, and Rocky Mountains.	Ranunculus gelidus