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