1	Perennials.		(2)
+	Annuals.		(39)
2 (1)	Nectaries 1 per corolla lobe.		(3)
+	Nectaries 2 per corolla lobe.		(12)
3 (2)	Flowers 5merous.		(4)
+	Flowers 4merous.		(5)
4 (3)	Corolla yellow-green, lobes 8-17 mm		3 Swertia erythrosticta
+	Corolla white, lobes 3-3.5 mm		47 Swertia rosularis
5 (3)	Plant densely tufted; stems 2-12 cm; inflorescences 1-7-flowered, umbel-like or reduced to a solitary terminal flower.		(6)
+	Plant with single robust stem; stems 12-100 cm; inflorescences many flowered, conical thyrse or verticillasterlike.		(9)
6 (5)	Nectary reduced to a flat gland patch without raised margin or fimbriae.		(7)
+	Nectary with raised fimbriate margin.		(8)
7 (6)	Plants 2-4 cm tall; petiole 0.8-1.8 cm; leaf blade ovate to suborbicular, 1veined; corolla 8-10 mm in diam., glabrous		1 Swertia handeliana
+	Plants 5-7 cm tall; petiole 5-6 cm; leaf blade oblong-spatulate, 3veined; corolla 12-14 mm in diam., puberulent		29 Swertia conaensis
8 (6)	Inflorescences racemelike or umbel-like, 1-7-flowered		27 Swertia multicaulis
+	Inflorescences scapose, 1flowered		28 Swertia scapiformis
9 (5)	Margin of leaves and calyx lobes minutely and somewhat irregularly laciniate; corolla brick red, drying yellow-green; nectaries margin with inflexed fimbriae		30 Swertia splendens
+	Margin of leaves and calyx lobes smooth; corolla pale yellow-green, pale blue-green, or pale purple; nectaries margin smooth.		(10)
10 (9)	Seeds wingless; inflorescences crowded, clusters of flowers ± contiguous		33 Swertia virescens
+	Seeds winged; inflorescences interrupted, cluster of flowers clearly separated from each other.		(11)
11 (10)	Seeds ellipsoid, minutely winged at both ends; nectaries ovate-triangular		31 Swertia verticillifolia
+	Seeds compressed, discoid winged; nectaries orbicular		32 Swertia hookeri
12 (2)	Flowers 4merous; plants with a taproot (rhizomatous in S. davidii).		(13)
+	Flowers 5merous (also 4merous in S. emeiensis); plant rhizomatous.		(16)
13 (12)	Inflorescences many flowered; nectaries radially elongated, with a narrow scale.		(14)
+	Inflorescences few flowered; nectaries pocket-shaped, with a triangular scale.		(15)
14 (13)	Plant rhizomatous; leaves basal and cauline; calyx shorter than corolla; corolla pale blue with blue veins		55 Swertia davidii
+	Plant not rhizomatous; leaves mostly basal; calyx longer than corolla; corolla dark purple		49 Swertia pianmaensis
15 (13)	Basal leaf blades narrowly spatulate to oblanceolate; calyx lobes 5-9 mm wide, bract-like		34 Swertia patens
+	Basal leaf blades linear-oblong; calyx lobes 2-3 mm wide, not bractlike		35 Swertia luquanensis
16 (12)	Nectary margin entire or each with 1 fimbria at base		2 Swertia divaricata
+	Nectary margin conspicuously fimbriate.		(17)
17 (16)	Seeds ± smooth, discoid winged or minutely winged at both ends; stem leaves always present, usually alternate toward base of stem, rarely all opposite.		(18)
+	Seeds longitudinally rugose, usually wingless (S. tibetica winged on edges, S. souliei winged at both ends); stem leaves absent or, if present, always opposite.		(24)
18 (17)	Flowers 4- (or 5)-merous, 2.5-4 cm in diam.; corolla lobes oblong, apex caudate; nectaries orbicular, margin with few erect fimbriae		4 Swertia emeiensis
+	Flowers 5merous, 1.5-2(-3) cm in diam.; corolla lobes narrowly elliptic to ovate-oblong, apex not caudate; nectaries cupular, margin with many fimbriae.		(19)
19 (18)	Calyx lobes as long as to longer than corolla or slightly shorter; seeds subglobose, with irregular narrow wings on edges and at both ends; inflorescences 4-7-flowered, rarely more flowered.		(20)
+	Calyx lobes shorter than corolla; seeds compressed, discoid winged; inflorescences many flowered.		(21)
20 (19)	Corolla pale yellow; pedicel 3-5.5 cm		5 Swertia calycina
+	Corolla dark blue to blue-purple, pedicel 1.2-3 cm		6 Swertia forrestii
21 (19)	All stem leaves alternate		7 Swertia obtusa
+	Stem leaves basally alternate but middle to upper leaves opposite.		(22)
22 (21)	Corolla pale purple to blue-purple, never spotted		8 Swertia perennis
+	Corolla pale yellow to yellow, often spotted.		(23)
23 (22)	Calyx ca. 2/3 as long as corolla; corolla lobes elliptic-lanceolate, 1.2-1.4 cm		9 Swertia veratroides
+	Calyx 1/2(-2/3) as long as corolla; corolla lobes oblong, 0.8-1.2 cm		10 Swertia connata
24 (17)	Stem leaves few or absent except for those subtending inflorescences (leaves mostly basal).		(25)
+	Stems with 2 to many pairs of leaves.		(29)
25 (24)	Basal leaves 3 or 4 pairs, usually linear-elliptic or oblanceolate; corolla lobes 2-3 mm wide.		(26)
+	Basal leaves 1 or 2 pairs, elliptic, spatulate, or ovate to oblong; corolla lobes 5-8 mm wide.		(27)
26 (25)	Corolla blue or blue-purple; calyx lobes with narrow indistinct membranous margin		11 Swertia graciliflora
+	Corolla yellow; calyx lobes with broad distinct membranous margin		12 Swertia marginata
27 (25)	Corolla dark blue		13 Swertia bifolia
+	Corolla pale yellow to yellow or yellow-green but pale blue on middle of inner surface.		(28)
28 (27)	Corolla lobes usually 0.9-1.5 cm; calyx lobes narrowly lanceolate, apex acuminate; corolla lobes lanceolate, apex acuminate to acute; ovary horizontally folded		14 Swertia przewalskii
+	Corolla lobes usually 1.5-2 cm; calyx lobes ovate-lanceolate, apex acute; corolla lobes oblong to elliptic, apex obtuse to rounded and erose; ovary smooth		15 Swertia wolfgangiana
29 (24)	Calyx lobes usually oblong-spatulate to elliptic, base narrowed, apex rounded; nectaries radially elongated		16 Swertia cuneata
+	Calyx lobes linear to ovate-lanceolate, base not narrowed, apex acuminate to acute; nectaries cupular or orbicular.		(30)
30 (29)	Stem upper leaves bractlike; nectaries orbicular; calyx lobes 6-8 mm.		(31)
+	Stem upper leaves not bractlike; nectaries cupular; calyx lobes (7-)9-20 mm.		(33)
31 (30)	Corolla pale yellow, with purple spots; basal leaves ovate; stem leaves 2-3 cm		19 Swertia rotundiglandula
+	Corolla dark purple; basal leaves spatulate to oblong-spatulate or narrowly lanceolate to linear-elliptic; stem leaves 4-12 cm.		(32)
32 (31)	Inflorescences a panicle; basal leaf petiole 2-2.5 cm, blade 3.5-6 cm, spatulate to oblong-spatulate		20 Swertia asarifolia
+	Inflorescences a thyrse, interrupted; basal leaf petiole 5-10 cm, blade 10-16 cm, narrowly lanceolate to linear-elliptic		21 Swertia elata
33 (30)	Inflorescences a narrow dense interrupted many-flowered thyrse; basal leaf blade 17-31 cm		17 Swertia kingii
+	Inflorescences paniculate or racemelike; basal leaf blade 2-14 cm.		(34)
34 (33)	Bases of stem leaf blades subamplexicaul.		(35)
+	Bases of stem leaf blades not subamplexicaul.		(37)
35 (34)	Basal leaf petiole 3-7 cm; stem leaves 2 or 3 pairs; leaf blade ovate-lanceolate		26 Swertia souliei
+	Basal leaf petiole 1-2.5 cm; stem leaves more than 3 pairs; leaf blade broadly linear, lanceolate, or linear-elliptic.		(36)
36 (35)	Calyx lobes 0.7-0.9 cm; corolla blue-purple, lobes 0.9-1.3 cm		22 Swertia gyacaensis
+	Calyx lobes 1.5-2 cm; corolla yellow, with blue in middle of outer surface, lobes 2-2.5 cm		25 Swertia younghusbandii
37 (34)	Plant 15-20 cm tall; corolla blackish purple		18 Swertia endotricha
+	Plant 30-100 cm tall; corolla blue or yellow.		(38)
38 (37)	Corolla pale blue to pale blue-gray, lobes (1-)1.3-1.5 cm, ca. 1.9 cm in fruit		23 Swertia wardii
+	Corolla yellow, lobes 2.5-2.8 cm		24 Swertia tibetica
39 (1)	Stems dichotomously branched from base; flowers in branch forks; each nectary produced into a very short spur on back of corolla lobe		36 Swertia dichotoma
+	Stems well defined, erect or ascending, with or without axillary branches; flowers both terminal and usually axillary; nectaries without an associated spur.		(40)
40 (39)	Filaments dilated laterally so as to be lanceolate to ovate, bases contiguous or fused into a tube around ovary.		(41)
+	Filaments not to slightly dilated at base, clearly separated from each other.		(46)
41 (40)	Nectaries 2 per corolla lobe, inverted (opening toward base of corolla), pocket-shaped, fimbriate		70 Swertia hispidicalyx
+	Nectaries 1 per corolla lobe, horseshoe-shaped and naked or oblong and with few divisions.		(42)
42 (41)	Calyx and corolla tubes distinct, 2.5-3.5 mm; nectary oblong, laciniate; style cylindric, 1.5-2 mm		75 Swertia racemosa
+	Calyx and corolla tubes indistinct, 0.5-1.5 mm; nectary horseshoe-shaped, naked; style filiform, 2.5-4 mm.		(43)
43 (42)	Filaments connate into a short tube surrounding ovary.		(44)
+	Filaments free.		(45)
44 (43)	Corolla blue-purple, reflexed at anthesis		71 Swertia ciliata
+	Corolla pale yellow-green, erect at anthesis		72 Swertia cincta
45 (43)	Calyx lobes leaflike, unequal, 2 larger and 3 smaller; corolla white, lobes margin lacerulate		73 Swertia pubescens
+	Calyx lobes not leaflike, only slightly unequal; corolla pale yellow, lobes margin entire		74 Swertia paniculata
46 (40)	Plants with 1 to few erect, robust, and narrowly 4winged main stems that have larger flowers and numerous weak branches with flowers 1/4-1/3 as large as those of main stem; filaments with a small scale at base		69 Swertia tetraptera
+	Plants with stems and flowers uniform, usually not branched from lowermost nodes; filaments without a scale at base.		(47)
47 (46)	Nectaries reduced to a naked gland patch.		(48)
+	Nectaries fimbriate or with laciniate margin.		(52)
48 (47)	Nectaries 1 per corolla lobe.		(49)
+	Nectaries 2 per corolla lobe.		(50)
49 (48)	Inflorescences rounded and lax; calyx somewhat campanulate, lobes spreading and ovate-triangular to ovate; corolla lobes narrowly oblong, 1.7-1.9 cm		37 Swertia shintenensis
+	Inflorescences usually narrow and dense; calyx rotate, lobes erect and lanceolate to ovate-lanceolate; corolla lobes narrowly elliptic to elliptic-lanceolate, 0.8-1 cm		38 Swertia cordata
50 (48)	Leaf blade broadly elliptic to ovate-lanceolate, 1-4(-5) cm wide; corolla with purple spots		39 Swertia bimaculata
+	Leaf blade linear, linear-lanceolate, or lanceolate, 0.2-0.7 cm wide; corolla unspotted or with yellow spots.		(51)
51 (50)	Calyx lobes ovate-lanceolate or lanceolate; corolla yellow, without spots, lobes oblong and apex acute; plants to 80 cm tall		40 Swertia matsudae
+	Calyx lobes linear to linear-oblong; corolla white, with yellow-green spots, lobes elliptic-lanceolate and apex acuminate and apiculate; plants to 40 cm tall		41 Swertia oculata
52 (47)	Nectaries pocket-shaped, with an orbicular scale and numerous minutely papillose short fimbriae sometimes hidden by the scale.		(53)
+	Nectaries triangular, radially elongated, or cupular, with a narrow scale and long or sometimes short glabrous fimbriae.		(57)
53 (52)	Nectaries 2 per corolla lobe.		(54)
+	Nectaries 1 per corolla lobe.		(55)
54 (53)	Stems ascending, 5-15 cm, cespitose, much branched at base; corolla white or pale purple, with dark blue-purple veins		42 Swertia patula
+	Stems erect, 15-45 cm, pyramidal, branched throughout; corolla pale blue, without dark veins		43 Swertia leducii
55 (53)	Calyx lobes shorter or equal to corolla; corolla white or pale yellow, with brown spots		44 Swertia angustifolia
+	Calyx lobes much longer than corolla; corolla yellow-green, with purple veins.		(56)
56 (55)	Leaf blade narrowed at base; seed coat spongy		45 Swertia nervosa
+	Leaf blade rounded at base; seed coat rugose		46 Swertia arisanensis
57 (52)	Flowers 3-5(-10) mm.		(58)
+	Flowers (7-)10-20 mm.		(62)
58 (57)	Nectaries 1 per corolla lobe		48 Swertia tenuis
+	Nectaries 2 per corolla lobe.		(59)
59 (58)	Style distinct, slender; flowers 4merous; nectaries radially elongated		50 Swertia membranifolia
+	Style indistinct, stout; flowers usually 5merous (occasionally 4merous in S. macrosperma), nectaries cupular.		(60)
60 (59)	Seeds 3 or 4 per capsule, 1.5-2 mm; nectaries with few fimbriae		51 Swertia macrosperma
+	Seeds many per capsule, less than 1 mm; nectaries with many fimbriae.		(61)
61 (60)	Calyx lobes elliptic-spatulate to elliptic; corolla lobes ovate, apex acute		52 Swertia zayueensis
+	Calyx lobes linear-lanceolate; corolla lobes ovate-lanceolate, apex acuminate		53 Swertia alba
62 (57)	Flowers 4merous (occasionally 5merous in S. kouitchensis).		(63)
+	Flowers 5merous.		(66)
63 (62)	Nectaries with short compound fimbriae		54 Swertia tetrapetala
+	Nectaries with long simple fimbriae.		(64)
64 (63)	Calyx as long as or longer than corolla, lobes unequal		56 Swertia kouitchensis
+	Calyx 1/2-2/3 as long as corolla, lobes subequal.		(65)
65 (64)	Plants regularly branched from near base so whole plant is pyramidal; corolla dark purple or pale yellow green to pale yellow		57 Swertia mussotii
+	Plants with cymes in spreading branched panicles; corolla pale blue		58 Swertia tozanensis
66 (62)	Calyx lobes bractlike, unequal, 3 larger and ovate, 2 smaller and ovate-lanceolate, all with prominent reticulate veins outside		59 Swertia delavayi
+	Calyx lobes not bractlike, subequal, linear to linear-lanceolate, without prominent reticulate veins outside.		(67)
67 (66)	Inflorescences usually reduced to single terminal flower, sometimes with additional flowers terminating short axillary branches		60 Swertia decora
+	Inflorescences a panicle with at least some (but usually all) flowers in leaf axils.		(68)
68 (67)	Corolla lobes not apiculate.		(69)
+	Corolla lobes apiculate.		(72)
69 (68)	Calyx more than 2/3 as long as corolla.		(70)
+	Calyx 1/2-2/3 as long as corolla.		(71)
70 (69)	Corolla 1-1.5 cm in diam.; nectaries with simple fimbriae		61 Swertia diluta
+	Corolla 1.5-2 cm in diam.; nectaries with compound fimbriae		62 Swertia pseudochinensis
71 (69)	Pedicel filiform; corolla pale blue; calyx lobes linear; nectaries triangular		63 Swertia yunnanensis
+	Pedicel linear; corolla white or rarely pale blue; calyx lobes linear-lanceolate; nectaries radially elongated		64 Swertia hickinii
72 (68)	Corolla white or yellow.		(73)
+	Corolla pale blue or dark purple.		(74)
73 (72)	Base of stem leaf blades subamplexicaul, margin ciliolate; corolla 1.5-1.7 cm in diam.		65 Swertia binchuanensis
+	Base of stem leaf blades tapered, margin not ciliolate; corolla 0.8-1.2 cm in diam.		66 Swertia punicea
74 (72)	Corolla dark purple		66 Swertia punicea
+	Corolla pale blue.		(75)
75 (74)	Stem leaf bases auriculate, subamplexicaul; inflorescences many-flowered panicles formed by the whole plant; pedicel stout, to 4 cm; corolla lobes 9-15 mm		67 Swertia franchetiana
+	Stem leaf bases cuneate, not subamplexicaul; inflorescences a narrow panicle with many ± fascicled flowers; pedicel slender, 0.3-0.5 cm; corolla lobes 5-7 mm		68 Swertia fasciculata