| 1 |
Abaxial surface of sepals with dense brown pubescence. |
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(2) |
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Abaxial surface of sepals glabrous or with colorless hairs. |
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(4) |
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| 2 (1) |
Basal leaf blades narrowly elliptic to lanceolate or oblanceolate; s Rocky Mountains. |
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30 Ranunculus macauleyi |
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Basal leaf blades orbiculate to reniform; Canadian Rocky Mountains and Arctic. |
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(3) |
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| 3 (2) |
Receptacle brown-pilose; basal leaf blades usually shallowly lobed, or unlobed with crenate margins. |
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29 Ranunculus sulphureus |
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Receptacle glabrous; basal leaf blades 3-parted. |
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28 Ranunculus nivalis |
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| 4 (1) |
Basal leaves deciduous before anthesis; nectary scale ciliate, petals 2–3 times as long as wide. |
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39a var. arizonicus |
| + |
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). |
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(5) |
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| 5 (4) |
Some or all basal leaf blades unlobed. |
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(6) |
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All basal leaf blades lobed or parted. |
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(14) |
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| 6 (5) |
Basal leaf margins entire or with 3 broad shallow rounded teeth; heads of achenes globose, 6–20mm wide. |
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49 Ranunculus glaberrimus |
| + |
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). |
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(7) |
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| 7 (6) |
Petals 1–3.5 mm. |
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(8) |
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Petals 4–18 mm. |
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(10) |
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| 8 (7) |
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. |
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44 Ranunculus micranthus |
| + |
Stems glabrous; receptacle pilose, sometimes sparsely so; base of roots never much swollen, 0.2–1.5 mm thick; leaf base ± cordate. |
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(9) |
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| 9 (8) |
Sepals hispid; achene beak 0.6–1 mm. |
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46 Ranunculus allegheniensis |
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Sepals glabrous; achene beak 0.1–0.2 mm. |
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45 Ranunculus abortivus |
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| 10 (7) |
Leaf blades wider than long; e of Great Plains, not in Great Lakes area. |
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(11) |
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Leaf blades at least as long as wide; Great Lakes area and Great Plains w to Great Basin. |
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(12) |
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| 11 (10) |
Pedicels glabrous (see also R. escholtzii with lobed leaves); se United States. |
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43a var. harveyi |
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Pedicels pubescent, sometimes sparsely so; e Canada. |
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36 Ranunculus allenii |
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| 12 (10) |
Sepals 5–8 × 3–7 mm; nectary scale ciliate, sometimes glabrous; leaf base cordate to broadly obtuse. |
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40 Ranunculus cardiophyllus |
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Sepals 3–6× 1.5–3mm; nectary scale glabrous; leaf base obtuse or acute to rounded. |
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(13) |
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| 13 (12) |
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. |
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37 Ranunculus inamoenus |
| + |
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. |
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38 Ranunculus rhomboideus |
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| 14 (5) |
Basal leaf blades dissected into linear segments. |
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(15) |
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Basal leaves at most 1×-divided, segments not linear. |
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(16) |
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| 15 (14) |
Roots slender, 0.8–1.4 mm thick; achene beak 1.2–1.7 mm. |
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32 Ranunculus adoneus |
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Roots 2–3 mm thick; achene beak 0.8–1.5 mm. |
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48 Ranunculus triternatus |
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| 16 (14) |
Some roots clavate and tuberous, 2.5–5 mm thick; basal leaf blades deeply divided into 3 oblanceolate segments. |
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47 Ranunculus jovis |
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Roots not clavate or tuberous, 0.1–1.6 mm thick; leaves various but not as above. |
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(17) |
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| 17 (16) |
Petals 7–15 mm. |
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(18) |
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Petals 1–8 mm. |
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(20) |
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| 18 (17) |
Pedicels glabrous. |
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31 Ranunculus eschscholtzii |
| + |
Pedicels pubescent. |
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(19) |
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| 19 (18) |
Heads of achenes globose to short-ovoid; basal leaves 3-parted with segments again lobed or parted, margins toothed; Greenland. |
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42 Ranunculus auricomus |
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Heads of achenes cylindric; basal leaves pedately (5–)7(–9)-parted or -divided, segments sometimes again lobed, margins never toothed; throughout n North America. |
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41a var. affinis |
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| 20 (17) |
Flowering stems 0.6–3.5 cm (sometimes longer in fruit); petals 1–3.5 mm. |
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34 Ranunculus pygmaeus |
| + |
Flowering stems (1–)4–15(–27) cm; petals 3–8 mm. |
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(21) |
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| 21 (20) |
Petals 6–16 mm; beak of achene straight, 0.6–1.8 mm; pedicels glabrous. |
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31 Ranunculus eschscholtzii |
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Petals 4–8 mm; beak of achene straight or curved, 0.3–0.7 mm; pedicels glabrous or pilose. |
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(22) |
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| 22 (21) |
Base of basal leaves obtuse; petals 5–8 mm; arctic Alaska, Canada, and Greenland. |
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35 Ranunculus sabinei |
| + |
Base of basal leaves nearly cordate to truncate; petals 4–5 mm; Alaska, Yukon, and Rocky Mountains. |
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33 Ranunculus gelidus |
