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1 Flowers sessile, opposite the petioles; sepals 3; petals 3; [section Polyanthemos]
..2 Petals 1-2 (-3) mm long; receptacles glabrous; [section Ranunculus]
......4 Achene with a few conical protuberances; petals 5-12 mm long; plant sparsely to densely hirsute; achenes 30-40 per head
......4 Achene with numerous short spines; petals (3-) 4-5 mm long; plant with a few, widely scattered, long hairs; achenes 40-60 per head
........5 Achenes 4-9 per head, in a single whorl; achene margins spiny, as also the faces; beak of the achene 2.5-3 mm long; [section Echinella]
..........6 Achene faces with short protuberances ca. 0.2 mm long; achene beak 0.8-1.0 mm long; peduncle usually longer than the subtending leaf
..........6 Achene faces with stout spines ca. 0.5 mm long; achene beak 2.0-2.5 mm long; peduncle usually shorter than the subtending leaf