1B. Herbs. Subgenus 2. Paeonia
	3A. Flowers 2-4 in a cyme or solitary but often with one or two undeveloped flower buds in axils; roots carrot-shaped. Section 2A. Albiflorae
	3B. Flowers solitary and terminal; roots fusiform-thickened or carrot-shaped.
		4A. Leaves mostly with bristles along veins above; leaflets finely segmented; leaflets plus segments (9-)21-340 in number; roots fusiform-thickened. Section 2B. Paeonia
		4B. Leaves always glabrous above; roots carrot-shaped or slightly fusiform-thickened.
			5A. Petals nearly as long as sepals (slighly longer or shorter); stems often branched; roots slighly fusiform-thickened. Section 2E. Onaepia
			5B. Petals much longer (>2 times) than sepals; stems simple
				6A. Lower leaves always biternate, with 9 leaflets; leaflets entire; carpels mostly 2 or 3, rarely 1, 4 or 5. Section 2C. Obovatae
				6B. Lower leaves biternate, with 9, rarely 8 or 7 leaflets; leaflets segmented or entire; leaflets plus segments 9-95, very rarely 8 or 7; carpels 2-5, rarely 6, 1, 7-10. Section 2D Corallinae