1	Plants dioecious		(2)
+	Florets bisexual		(3)
2 (1)	Stems glabrous or cobwebby-felted; leaves divided or undivided but if undivided then base cuneate.		45 C. arvense
+	Stems hairy; leaves undivided with base auriculate and semiamplexicaul.		46 C. shihianum
3 (1)	Some of phyllaries expanded laterally into membranous wings or distally into a scarious appendage		(4)
+	Phyllaries lacking wings and scarious appendage		(12)
4 (3)	Leaves adaxially rough and spinulose		(5)
+	Leaves adaxially smooth or covered with hair-tipped papillae and slightly rough but not spinulose		(6)
5 (4)	Leaves abaxially densely felted; outer and middle phyllaries unwinged but inner phyllaries expanded into a scarious white or pink appendage.		37 C. leducii
+	Leaves abaxially sparsely cobwebby; outer and middle phyllaries with a margin expanded into yellowish scarious wings.		44 C. chrysolepis
6 (4)	Bracts surrounding capitula with pectinately arranged long pungent spines		(7)
+	Bracts surrounding capitula (if present) without pectinately arranged long pungent spines		(9)
7 (6)	Margin of middle phyllaries not laterally expanded into wings but inner phyllaries apically expanded.		41 C. argyracanthum
+	Margin of middle phyllaries expanded above base into denticulate to lacerate scarious wings		(8)
8 (7)	Outer phyllaries unwinged but usually with pectinately spinulose margin, middle phyllaries with irregularly lacerate scarious wings.		42 C. glabrifolium
+	Outer and middle phyllaries with regularly denticulate-lacerate wings.		43 C. sieversii
9 (6)	Leaves green, concolorous, and glabrous or with sparse hairs along veins		(10)
+	Leaves abaxially grayish white and cobwebby or felted, adaxially green, glabrous, papillose, or with scattered crispate hairs		(11)
10 (9)	Stems below capitulum felted.		33 C. tianmushanicum
+	Stems with crispate hairs, below capitulum also ± cobwebby.		34 C. chinense
11 (9)	Leaves undivided or rarely slightly lobed in proximal third.		35 C. lineare
+	Leaves pinnately lobed to pinnatipartite at least in proximal half.		36 C. shansiense
12 (3)	Outer and middle phyllaries villous or hirsute with multicellular hairs or bristles		(13)
+	Involucre glabrous, sparsely cobwebby, or lanate, phyllaries never hirsute or villous		(14)
13 (12)	Leaves concolorous, greenish, with sparse to dense bristles.		15 C. fuscotrichum
+	Leaves discolorous, abaxially grayish white and densely felted, adaxially green and glabrous.		16 C. muliense
14 (12)	Involucre densely lanate		(15)
+	Involucre glabrous or cobwebby		(16)
15 (14)	Leaves adaxially with scattered spinules or smooth, pinnately divided, segments elliptic, semiorbicular, or ovate.		7 C. eriophoroides
+	Leaves adaxially rough with sparse to dense spinules, bipinnatipartite, segments triangular to triangular-lanceolate.		12 C. lidjiangense
16 (14)	Leaves adaxially rough and spinulose		(17)
+	Leaves adaxially smooth and not spinulose		(22)
17 (16)	Stems winged.		14 C. vulgare
+	Stems unwinged		(18)
18 (17)	Leaf segments elliptic, semiorbicular, or ovate		(19)
+	Leaf segments lanceolate to narrowly triangular		(20)
19 (18)	Leaves discolorous, abaxially grayish white, adaxially green.		8 C. subulariforme
+	Leaves concolorous, green.		9 C. verutum
20 (18)	Leaves concolorous, green to yellowish green.		10 C. chlorolepis
+	Leaves discolorous, abaxially grayish white, adaxially greenish		(21)
21 (20)	Outer and middle phyllaries ending in a subulate spine 8-13 mm, outer phyllaries not much shorter than inner.		11 C. botryodes
+	Outer phyllaries ending in a spinule or acumen to 2 mm, outer phyllaries much shorter than inner.		13 C. interpositum
22 (16)	Corolla yellow or white		(23)
+	Corolla red to purple		(24)
23 (22)	Plants 80-150 cm tall; involucre 4-4.5 cm in diam.; leaves concolorous.		6 C. monocephalum
+	Plants 45-50 cm tall; involucre ca. 2 cm in diam.; leaves discolorous.		40 C. alberti
24 (22)	Plants stemless with all leaves basal		(25)
+	Plants with leafy stems at least 20 cm tall		(26)
25 (24)	Petiole unwinged or with discontinuous wing; outer and middle phyllaries narrowly triangular, pectinately fringed with spinules.		4 C. souliei
+	Petiole with continuous wing; outer and middle phyllaries ovate to lanceolate, margin not spinulose.		23 C. esculentum
26 (24)	Stems winged.		29 C. alatum
+	Stems unwinged		(27)
27 (26)	Outer phyllaries bractlike, dissimilar from and almost twice as long as middle and inner phyllaries.		1 C. bracteiferum
+	Outer phyllaries not bractlike, similar to and not longer than middle ones		(28)
28 (27)	Outer and middle phyllaries pectinately fringed with spinules		(29)
+	Outer and middle phyllaries not fringed with spinules		(31)
29 (28)	Leaves abaxially cobwebby or glabrous, adaxially glabrous.		5 C. fargesii
+	Leaves not cobwebby but with crispate multicellular hairs		(30)
30 (29)	Involucre ca. 4 cm in diam., sparsely cobwebby.		2 C. leo
+	Involucre ca. 2 cm in diam., glabrous.		3 C. henryi
31 (28)	Bracts surrounding capitula reduced to pectinately arranged long pungent spines		(32)
+	Bracts surrounding capitula (if present) not reduced to pectinately arranged long pungent spines		(34)
32 (31)	Leaves concolorous, green, glabrous.		38 C. semenowii
+	Leaves discolorous, abaxially grayish green to whitish and cobwebby or felted, adaxially greenish and hairy		(33)
33 (32)	Outer and middle phyllaries narrowed into a 0.1-0.5 cm spine.		24 C. periacanthaceum
+	Outer and middle phyllaries tipped with a ca. 3 cm spine.		39 C. sairamense
34 (31)	Phyllaries in ca. 10 rows; corolla tube more than twice as long as limb.		32 C. pendulum
+	Phyllaries in 5-8 rows; corolla tube shorter or at most slightly longer than limb		(35)
35 (34)	Leaves undivided, margins entire or toothed with spinules of at most 2 mm		(36)
+	Leaves pinnately divided (or at least lobed), margin usually distinctly spiny		(41)
36 (35)	Outer and middle phyllaries with an apical spine 3-7 mm.		30 C. vernonioides
+	Phyllaries with an apical spinule of at most 1 mm		(37)
37 (36)	Leaves discolorous, abaxially grayish to white and felted		(38)
+	Leaves concolorous, abaxially green and glabrous or with multicellular hairs but not felted		(39)
38 (37)	Lower cauline leaves petiolate, to 3 cm wide, narrowed at base.		19 C. vlassovianum
+	All cauline leaves sessile, at least 4 cm wide, semiamplexicaul.		21 C. helenioides
39 (37)	Involucre ovoid.		18 C. serratuloides
+	Involucre campanulate		(40)
40 (39)	Outer and middle phyllaries abaxially with a dark resinous gland.		17 C. viridifolium
+	Phyllaries lacking a resinous gland.		20 C. fanjingshanense
41 (35)	At least upper cauline leaves discolorous, abaxially gray to white and felted, adaxially ± green		(42)
+	Leaves concolorous, abaxially green and glabrous or with sparse to dense multicellular hairs but not felted		(43)
42 (41)	Lower cauline leaves petiolate, often concolorous; capitula corymbose.		25 C. maackii
+	All cauline leaves sessile, discolorous; capitula racemose.		26 C. racemiforme
43 (41)	Involucre 2-3 cm in diam		(44)
+	Involucre 3-4.5 cm in diam		(45)
44 (43)	Cauline leaves sessile; basal leaves present at anthesis.		22 C. japonicum
+	Lower and middle cauline leaves petiolate; basal leaves withered at anthesis.		28 C. schantarense
45 (43)	Corolla tube less than 1/2 as long as limb; outer and middle phyllaries abaxially with a dark resinous gland.		27 C. fangii
+	Corolla tube slightly longer than limb; phyllaries lacking a resinous gland.		31 C. handelii