1	Leaf blade ovate to broadly ovate, rarely subelliptic on brachyblasts, (2.5-)3-7.5 mm wide, margin serrate, veins 3		(2)
+	Leaf blade linear, oblong, linear-lanceolate, or ovate-lanceolate, rarely subelliptic, 1-6(-15) mm wide, margin entire, vein 1, never 3, rarely with weak lateral veins		(9)
2 (1)	Leaves alternate or tufted; capitulum solitary		(3)
+	Leaves alternate; capitula many, rarely few, in glomerulate or corymbose synflorescences		(4)
3 (2)	Brachyblast leaves on branchlets elliptic; capitula terminal on branchlets.		1 P. scandens
+	Brachyblast leaves on branchlets ovate; capitula terminal on long shoots.		2 P. simozawae
4 (2)	Capitulum 1-flowered; involucres cylindric, ca. 3 mm in diam.		3 P. desmocephala
+	Capitulum 4-12-flowered; involucres campanulate, 5-12 mm in diam		(5)
5 (4)	Phyllary apices mucronate to acuminate, pungent.		4 P. pungens
+	Phyllary apices rounded to obtuse, never pungent		(6)
6 (5)	Capitula solitary, paired, or in corymbose synflorescences; leaf blade base broadly cuneate, obtuse, or truncate		(7)
+	Capitula 3-8 in glomerulate synflorescences; leaf blade base cordate, rarely truncate		(8)
7 (6)	Florets all bisexual; involucres narrowly campanulate, 5-6 mm in diam.; achenes glabrous or apices sparsely pubescent, pappus dark white.		5 P. henanensis
+	Marginal florets female, central florets bisexual; involucres broadly campanulate, ca. 12 mm in diam.; achenes densely hairy, pappus brownish.		6 P. corymbosa
8 (6)	Leaf blade apex mucronate or obtuse; florets 9-12 per capitulum.		7 P. pubescens
+	Leaf blade apex acuminate to caudate; florets 4 or 5 per capitulum.		8 P. cordifolia
9 (1)	Phyllaries multiseriate, at least 6- or 7-seriate; leaf margin strongly revolute		(10)
+	Phyllaries 3- or 4-seriate, rarely 5-seriate, few; leaf blade flat		(13)
10 (9)	Capitula many and small, 10-15 × 7-10 mm, solitary and terminal on branchlets or subtended by tufted leaves; florets 4-6 per capitulum		(11)
+	Capitula few and large, 2.5-3 × 1.5-2.5 cm, solitary and terminal on branches; florets 7-11 per capitulum		(12)
11 (10)	Leaves on branchlets homogeneous, leaf margin strongly revolute, terete, apex mucronate.		9 P. phylicoides
+	Leaves on branchlets heterogeneous, leaf margin strongly or slightly revolute, dimorphic, one form terete, other form oblong or spatulate-oblong, apex obtuse or rounded.		10 P. berberidoides
12 (10)	Capitula terminal, long pedunculate; phyllaries ca. 6-seriate; leaves subterete.		11 P. monocephala
+	Capitula terminal or axillary, sessile; phyllaries 16-18-seriate; leaves on branchlets oblong.		12 P. tsoongiana
13 (9)	Capitula 1-flowered		(14)
+	Capitula multiflowered or with only 2 florets in female plants		(15)
14 (13)	Leaf blade oblong to linear, 11-40 × 2-5 mm; capitula solitary, terminal on branchlets; phyllaries 3-seriate.		13 P. uniflora
+	Leaf blade elliptic or obovate, 2-12 × 1-6 mm; capitula many, in leafy panicles, axillary or terminal; phyllaries 5-7-seriate.		14 P. bodinieri
15 (13)	Involucres narrow, 2-3 mm in diam.		15 P. discolor
+	Involucres wide, 5-8 mm in diam		(16)
16 (15)	Leaves without lateral veins and reticulate veins.		16 P. angustifolia
+	Leaves with obvious lateral veins and reticulate veins.		17 P. sinensis