Plants usually ± hispid, sometimes glabrous. Stems erect to decumbent, sometimes stoloniferous, sometimes bulbous-based, without bulbils. Roots basal, sometimes also nodal, sometimes tuberous. Leaves basal and cauline, petiolate; basal deeply parted or compound (except sometimes in R. orthorhynchus var. bloomeri), blades with segments lobed or parted, margins toothed; cauline deeply parted or compound, similar to basal or with shorter petioles and/or blades with narrower segments (rarely poorly developed in R. fascicularis). Inflorescences 1-50-flowered cymes. Flowers pedicellate; sepals deciduous soon after anthesis, 5 (sometimes 6 in R. occidentalis var. hexasepalus); petals always present, yellow, sometimes abaxially reddish, rarely poorly developed; nectary scale attached basally, free from petal for at least 1/2 its length, forming flap covering nectary (or sometimes attached on 3 sides, forming pocket in R. recurvatus), glabrous, free margin entire; style present. Fruits achenes, 1-locular; achene body discoid, strongly flattened, 3-15 times as wide as thick, not prolonged beyond seed; wall thick, not ornamented; margin low or high narrow ridge or wing; beak much shorter than achene body.

Distribution

Worldwide except lowland tropics.

Discussion

Species ca. 100 (19 in the flora).

Selected References

None.

Lower Taxa

Ranunculus acriformis, Ranunculus acris, Ranunculus austro-oreganus, Ranunculus bulbosus, Ranunculus californicus, Ranunculus canus, Ranunculus fascicularis, Ranunculus fasciculatus, Ranunculus hispidus, Ranunculus macounii, Ranunculus macranthus, Ranunculus occidentalis, Ranunculus orthorhynchus, Ranunculus pacificus, Ranunculus pensylvanicus, Ranunculus recurvatus, Ranunculus repens, Ranunculus turneri, Ranunculus uncinatus

Key

1	Petals 2-6 mm, usually no longer than sepals (sometimes longer than sepals in R. uncinatus).	> 2
1	Petals (6-)7-26 mm (rarely shorter in R. occidentalis and R. canus, in which petals are much longer than sepals).	> 5
2	Basal leaves simple and lobed or parted.	> 3
2	Basal leaves compound.	> 4
3	Receptacle glabrous; base of stem not bulbous; w North America.	Ranunculus uncinatus
3	Receptacle hispid; base of stem bulbous, cormlike; e North America.	Ranunculus recurvatus var. recurvatus
4	Petals 2-4 × 1-2.5 mm; heads of achenes cylindric, 5-7 mm wide.	Ranunculus pensylvanicus
4	Petals 4-6 × 3.5-5 mm; heads of achenes globose to ovoid, 7-10 mm wide.	Ranunculus macounii
5	Sepals spreading, sometimes reflexed from base with age.	> 6
5	Sepals reflexed along well-defined transverse fold 1-3 mm above base.	> 12
6	Basal leaves deeply parted or dissected, ultimate segments linear to broadly linear, margins entire (occasionally a lobe reduced to large tooth); Rocky Mountains.	Ranunculus acriformis var. acriformis
6	Basal leaves variously parted or compound but not as above, segments seldom linear, margins toothed; widespread.	> 7
7	Leaf blades simple, 3-5-parted or -divided.	> 8
7	Leaf blades 3-5-foliolate.	> 9
8	Basal leaf blades pentagonal in outline; beak of achene 0.2-1 mm; widespread.	Ranunculus acris
8	Basal leaf blades cordate to reniform in outline; beak of achene 1.6-2 mm; Mackenzie Delta to ne Alaska.	Ranunculus turneri
9	Tuberous roots present.	> 10
9	Tuberous roots absent.	> 11
10	Petals 10-22; c Texas.	Ranunculus macranthus
10	Petals 5(-7); widespread, e North America.	Ranunculus fascicularis
11	Beak of achene curved, 0.8-1.2 mm; stems decumbent to creeping.	Ranunculus repens
11	Beak of achene straight or somewhat curved, 0.8-2.6 mm; stems erect to decumbent.	Ranunculus hispidus
12	Petals 8-22; Pacific Coast, Arizona, Texas.	> 13
12	Petals 5-7; widespread.	> 17
13	Tuberous roots absent; beak of achene lanceolate to deltate-apiculate, curved, 0.2-1.6 mm; California to British Columbia.	> 14
13	Tuberous roots present; beak of achene subulate, straight, (1.8-)2-4 mm (but sometimes deciduous); Texas, Arizona.	> 16
14	Achenes 3.4-4.2 mm, beak deltate or lance-deltate; Transverse Ranges, s California.	Ranunculus canus var. ludovicianus
14	Achenes 1.8-3.2 mm, beak lanceolate; California to British Columbia.	Ranunculus californicus
15	Beak of achene 1.2-1.6 mm; sepals 5-6; Queen Charlotte Islands, British Columbia.	Ranunculus occidentalis var. hexasepalus
15	Beak of achene 0.2-0.8 mm; sepals 5; California, Oregon, Mexico.	Ranunculus californicus
16	Petals 2-5 mm wide; achenes 2-2.4 mm wide, margins forming ribs or narrow wings 0.1-0.4 mm wide; sepals always reflexed; Arizona, trans-Pecos Texas.	Ranunculus fasciculatus
16	Petals 4-9 mm wide; achenes 2.8-3.4 mm wide, margins forming narrow ribs 0.4-0.6 mm wide; sepals spreading or weakly reflexed; Edwards Plateau, Texas.	Ranunculus macranthus
17	Receptacle glabrous; basal leaves 3-parted or -foliolate, segments or leaflets linear to cuneate.	> 18
17	Receptacle hispid; basal leaves usually pinnately 3-7-foliolate (sometimes merely 3-parted with orbiculate to ovate segments in Ranunculus orthorhynchus var. bloomeri).	> 21
18	Beak of achene deltate or lance-deltate, curved; Sacramento Valley, California.	Ranunculus canus var. canus
18	Beak of achene lanceolate to lance-subulate, straight or curved; widespread.	> 19
19	Basal leaves deeply 3-divided, segments again deeply parted, ultimate segments linear or nearly so; Rocky Mountains.	Ranunculus acriformis var. montanensis
19	Basal leaves deeply 3-parted to 3-foliolate, margins of segments or leaflets toothed or shallowly lobed, ultimate lobe triangular or broadly lanceolate; Pacific Slope.	> 20
20	Petals yellow on both surfaces; widespread.	Ranunculus occidentalis
20	Petals reddish abaxially; sw Oregon.	Ranunculus austro-oreganus
21	Beak of achene oblong or triangular, curved, 0.2-0.8 mm; introduced weeds.	> 22
21	Beak of achene lanceolate or subulate, straight or somewhat curved (sometimes tip weakly hooked in R. pacificus), (0.8-)1-3.8(-4.8) mm; native.	> 23
22	Base of stem bulbous, cormlike; petals 9-13 × 8-11 mm.	Ranunculus bulbosus
22	Base of stem not bulbous; petals 7-10 × 4-8 mm.	Ranunculus sardous
23	Stems decumbent, sometimes rooting at nodes; e North America.	Ranunculus hispidus var. nitidus
23	Stems erect to decumbent, never rooting at nodes; w North America.	> 24
24	Beak of achene 1-1.8 mm; leaflets lobed; Alaska panhandle.	Ranunculus pacificus
24	Beak of achene 2-3.8(-4.8) mm (1.8-2.2 mm in var. bloomeri, with unlobed leaflets); throughout w North America.	Ranunculus orthorhynchus