1	Fruiting calyx with 5, equal or subequal straight teeth.		(2)
+	Fruiting calyx with subequal teeth or 2-lipped, recurved.		(13)
2 (1)	Fruiting calyx tubular or tubular-campanulate to ovoid; inflorescences pyramidal paniculate.		(3)
+	Fruiting calyx campanulate to broadly campanulate; inflorescences loosely paniculate.		(8)
3 (2)	At least some leaves in whorls of 3 or 4		1 Isodon ternifolius
+	Leaves always opposite.		(4)
4 (3)	Stems and inflorescences densely, spreading, purplish or brownish, villous-velutinous or softly tomentose; leaves corrugate.		(5)
+	Stems and inflorescences with indumentum not as above; leaves not or only slightly rugulose.		(6)
5 (4)	Leaves ovate to triangular-ovate, 1.5-7 × 1-4 cm; petiole 2-8 mm; corolla purple to whitish blue		2 Isodon enanderianus
+	Leaves triangular-ovate, 1-2.5 × 1-2.5 cm; petiole 15-25 mm; corolla white		3 Isodon brevifolius
6 (4)	Leaves long petiolate, slightly pubescent along midribs and veins; panicles without floral leaves; calyx gray lanate, glabrescent and tubular in fruit		4 Isodon eriocalyx
+	Leaves sessile or short petiolate; inflorescence and calyx not as above.		(7)
7 (6)	Leaves ovate, sometimes cordate, 1.5-5 × 0.8-4.5 cm; adaxially puberulent or finely pilose; abaxially gray tomentose; fruiting calyx densely pilose, ovoid		5 Isodon phyllostachys
+	Leaves broadly ovate, 7-17 cm, ca. 1/2 as wide as long; abaxially densely strigose, sparsely glandular; calyx pubescent		6 Isodon pantadenius
8 (2)	Leaves lanceolate to narrowly lanceolate; calyx teeth lanceolate; nutlets apex pubescent		7 Isodon nervosus
+	Leaves broadly ovate to ovate-lanceolate; calyx teeth triangular; nutlets glabrous.		(9)
9 (8)	Fruiting calyx as long as wide; nutlets glandular		8 Isodon amethystoides
+	Fruiting calyx longer than wide; nutlets not glandular.		(10)
10 (9)	Terminal panicle few flowered, ca. 2 cm		9 Isodon websteri
+	Terminal panicle spreading, many flowered.		(11)
11 (10)	Adaxial leaf surface sparsely puberulent, abaxial surface whitish pilose along midrib and veins; calyx with minute hairs, glabrescent especially in fruit		10 Isodon inflexus
+	Leaves sparsely puberulent, glandular or glabrescent; calyx densely pubescent.		(12)
12 (11)	Leaves ovate to ovate-lanceolate, ± glabrescent, apex subacuminate, base cuneate, coarsely incurved, serrate; calyx densely whitish pubescent, teeth equal to calyx tube in length; stamens and style included; nutlets apex whitish barbate		11 Isodon serra
+	Leaves ovate to broadly ovate, sparsely puberulent, glandular; apical tooth ovate to lanceolate, apex acuminate, base broadly cuneate to abruptly attenuate, acutely serrate to crenate-dentate; calyx densely appressed whitish pubescent, bluish (especially in var. glaucocalyx), teeth shorter than calyx tube; stamens and style exserted; nutlets apex verruculose		12 Isodon japonicus
13 (1)	Cymes few flowered, axillary, in widely spaced verticillasters or in terminal racemose panicles; corolla tube conspicuously pouched or spurred on upper side near base; fruiting calyx conspicuously 2-lipped.		(14)
+	Cymes loosely many flowered, often conspicuously pedunculate, rarely in a dense verticillaster; corolla tube subequal or saccate, never short spurred on upper side near base; fruiting calyx with 5 subequal teeth or 2-lipped.		(18)
14 (13)	Leaves narrowly lanceolate to oblong, 3 × or more longer than broad.		(15)
+	Leaves much narrower, 2 × or less longer than broad.		(16)
15 (14)	Corolla to 8 mm, tube conspicuously pouched, to 2 mm in diam. on upper side near base, abruptly declinate above base, slightly constricted, ca. 1.2 mm in diam. at throat		73 Isodon gibbosus
+	Corolla ca. 7 mm, tube pouched on upper side near base, not abruptly declinate above base, throat subequal to tube		74 Isodon lungshengensis
16 (14)	Cymes in axils of mid and upper cauline leaves not reduced upwards, in many widely spaced verticillasters		75 Isodon melissoides
+	Cymes in axils of floral leaves gradually reduced toward branch apex, in terminal spicate panicles.		(17)
17 (16)	Petiole to 4.5 cm; corolla tube abruptly spurred on upper part near base, spur ca. 3 mm wide, conspicuously exserted, throat ca. 1.5 mm wide		76 Isodon brevicalcaratus
+	Petiole 0.2-1 cm; corolla tube saccate on upper part above base, tube equal in width elsewhere, ca. 2 mm in diam. at throat		77 Isodon adenanthus
18 (13)	Corolla 1.2-2.0 cm, tube 2 × or more longer than limb.		(19)
+	Corolla less than 1.2 cm, to 2 × as long as limb if tube stout.		(24)
19 (18)	Fruiting calyx conspicuously 2-lipped; corolla tube ca. 3 × longer than limb		13 Isodon longitubus
+	Fruiting calyx inconspicuously 2-lipped; corolla tube less than 3 × longer than limb.		(20)
20 (19)	Plants less than 30 cm tall; cymes 1-3-flowered, in narrow terminal panicles		14 Isodon gesneroides
+	Plants more than 30 cm tall; cymes 3- to many flowered, in ± spreading panicles.		(21)
21 (20)	Calyx broadly campanulate, purplish or dark purple-red.		(22)
+	Calyx campanulate, not tinged purplish.		(23)
22 (21)	Panicles strongly spreading, to 30 × 8-9 cm; pedicels 2-7 mm		15 Isodon forrestii
+	Panicles slightly spreading, (6-)10-15(-20) cm; floral leaves gradually becoming small bracts at apex; pedicels 1-3 mm		16 Isodon irroratus
23 (21)	Leaves rhombic, coarsely crenate-serrate above middle; petioles to 3.5 cm		17 Isodon wardii
+	Leaves narrowly ovate, crenate-dentate above basal 1/3; petioles less than 1 cm		18 Isodon bulleyanus
24 (18)	Fruiting calyx conspicuously 2-lipped.		(25)
+	Fruiting calyx with 5 equal or subequal teeth or inconspicuously 2-lipped.		(41)
25 (24)	Calyx lips extending to middle of calyx.		(26)
+	Calyx lips extending below middle of calyx.		(31)
26 (25)	Cymes in narrow panicles.		(27)
+	Cymes in spreading panicles.		(29)
27 (26)	Leaf blade base cordate; panicles secund		58 Isodon secundiflorus
+	Leaf blade base not cordate; panicles not secund.		(28)
28 (27)	Stamens included; lower corolla lip usually longer than corolla tube		56 Isodon coetsa
+	Stamens slightly exserted; lower corolla lip shorter than corolla tube		57 Isodon phyllopodus
29 (26)	Leaf blade base cordate		59 Isodon sculponeatus
+	Leaf blade base broadly cuneate to subcuneate, never cordate.		(30)
30 (29)	Terminal panicles to 30 × 20 cm, of 5-11-flowered cymes		60 Isodon megathyrsus
+	Terminal panicles 6-10(-15) × ca. 2.5 cm, of 3-5-flowered cymes		61 Isodon henryi
31 (25)	Cymes in spreading panicles.		(32)
+	Cymes in racemose or falsely racemose narrow panicles.		(35)
32 (31)	Leaf blade base ± shallow cordate.		(33)
+	Leaf blade base not cordate.		(34)
33 (32)	Teeth of fruiting calyx broadly triangular, apex acute; filaments basally pilose		69 Isodon scrophularioides
+	Teeth of fruiting calyx triangular to lanceolate-triangular, apex acuminate; filaments bearded below middle		70 Isodon flabelliformis
34 (32)	Stem shallowly grooved, densely retrorse puberulent; leaves very broadly ovate to oblate-ovate, apex rounded, margin crenate-serrate, apical tooth acute; corolla reddish purple or white		71 Isodon latifolius
+	Stem strongly grooved, puberulent on angles otherwise glabrous with scattered glands; leaves broadly ovate to ovate-orbicular, apex acuminate, margin coarse serrate or double serrate, apical tooth acuminate; corolla white		72 Isodon weisiensis
35 (31)	Leaves crenate-serrate.		(36)
+	Leaves coarsely serrate, dentate, or serrate-dentate.		(38)
36 (35)	Corolla less than 5.5 mm		66 Isodon rosthornii
+	Corolla more than 5.5 mm.		(37)
37 (36)	Stem densely retrorse white puberulent along angles; corolla gray or reddish, to 10 mm		67 Isodon liangshanicus
+	Stem appressed pubescent; corolla purple or purple-red, ca. 8 mm		68 Isodon macrocalyx
38 (35)	Inflorescences racemose or falsely racemose (in latter case basal cymes of inflorescence each with 3 flowers and a short peduncle), terminal and axillary, elongated, 8-20 cm		62 Isodon racemosus
+	Inflorescences ± conspicuously narrow paniculate.		(39)
39 (38)	Leaf apex long acuminate, sometimes ± excised		63 Isodon excisoides
+	Leaf apex not long acuminate, excised.		(40)
40 (39)	Plants densely white pilose; leaves dentate-serrate		64 Isodon albopilosus
+	Plants sparsely white puberulent; leaves coarsely serrate		65 Isodon grosseserratus
41 (24)	Leaf apex conspicuously excised.		(42)
+	Leaf apex not excised.		(43)
42 (41)	Abaxial leaf surface densely hairy; apical leaf tooth narrowly lanceolate, 2-2.5 cm, slightly cuneate, not extending to midrib of blade at base; cymes 10-15-flowered		19 Isodon macrophyllus
+	Abaxial leaf surface sparsely hairy or subglabrescent; apical leaf tooth caudate, 4-6 cm, cuneate, extending to midrib of blade at base, entire or 1- to few serrate; cymes (1-)3-5-flowered		20 Isodon excisus
43 (41)	Fruiting calyx with 5 short teeth to 1/3 as long as fruiting calyx tube; corolla tube spreading or straight.		(44)
+	Fruiting calyx with 5 long teeth more than 1/3 as long as fruiting calyx tube; corolla tube declinate.		(49)
44 (43)	Corolla mostly yellow or yellowish, rarely rose		21 Isodon flavidus
+	Corolla purplish, blue, rose, or white.		(45)
45 (44)	Inflorescences gray tomentulose		22 Isodon calcicolus
+	Inflorescences with hairs not as above, hairs never gray.		(46)
46 (45)	Leaves narrowly lanceolate to elliptic-lanceolate, base narrowly cuneate, margin ± remotely serrate above middle		23 Isodon walkeri
+	Leaves ovate to ovate-lanceolate, base rounded to cuneate-attenuate, margin crenate or serrate except at base.		(47)
47 (46)	Inflorescences papillate velutinuous; leaves scaly hirsute especially on midrib and veins of abaxial surface		24 Isodon yuennanensis
+	Inflorescences not papillate velutinous; leaves villous or hirtellous especially on midrib and veins of abaxial surface.		(48)
48 (47)	Calyx densely villous		25 Isodon hispidus
+	Calyx sparsely villous basally		26 Isodon lophanthoides
49 (43)	Calyx teeth extending to middle of calyx or more.		(50)
+	Calyx with small teeth never extending to middle of calyx.		(55)
50 (49)	Cymes in interrupted spikelike panicles		50 Isodon interruptus
+	Cymes in ± continuous narrow spikes.		(51)
51 (50)	Calyx teeth apex filiform-acuminate		51 Isodon barbeyanus
+	Calyx teeth apex never filiform-acuminate.		(52)
52 (51)	Leaves subcircular to ovate-oblong, 1.2-1.8 × 0.6-1.8 cm, strongly netted		52 Isodon scoparius
+	Leaves larger, inconspicuously netted.		(53)
53 (52)	Floral leaves bractlike; calyx teeth ovate-triangular		53 Isodon muliensis
+	Floral leaves ± similar to stem leaves; calyx teeth narrowly lanceolate to lanceolate-triangular.		(54)
54 (53)	Panicles terminal, 1.5-13 cm, cymes 3-5(-11)-flowered, peduncle 2-5(-9) mm		54 Isodon setschwanensis
+	Panicles terminal or axillary, to 20(-34) cm, cymes 3-15(-23)-flowered, peduncle 4-25(-48) mm		55 Isodon angustifolius
55 (49)	Branchlets, leaves, and calyces sparsely hairy; leaves usually not corrugate.		(56)
+	Branchlets, leaves, and calyces variously dense hairy; leaves mostly corrugate.		(62)
56 (55)	Stems ascending; branches and petioles densely pilose; stem leaves triangular-ovate, petiole 1.5-3 cm		43 Isodon flexicaulis
+	Stems erect; branches and petioles sparsely pilose; stem leaves broadly ovate to oblong-lanceolate, petiole less than 1.5 cm.		(57)
57 (56)	Stem leaves less than 2 cm.		(58)
+	Stem leaves more than 2 cm.		(60)
58 (57)	Stem leaves broadly truncate-ovate to subcircular, glandular puberulent		44 Isodon glutinosus
+	Stem leaves mostly ovate, subrhombic-ovate, to oblong-lanceolate, sometimes broadly ovate, not glandular hairy.		(59)
59 (58)	Corolla white, ca. 6 mm, tube included; calyx densely white pilose inside on teeth		45 Isodon medilungensis
+	Corolla purplish, ca. 9 mm, tube exserted; calyx glabrous inside		46 Isodon pharicus
60 (57)	Stems subcylindric, densely glandular pubescent; calyx teeth triangular, apex conspicuously mucronate		47 Isodon mucronatus
+	Stems obtusely 4-angled, pubescent or glandular pubescent; calyx teeth ovate-triangular, apex acute, never mucronate.		(61)
61 (60)	Branchlets and petioles densely gray pubescent, not glandular pubescent		48 Isodon silvaticus
+	Branchlets and petioles densely glandular pubescent		49 Isodon pleiophyllus
62 (55)	Branchlets, leaves, and calyces densely stellate tomentose or stellate lanate.		(63)
+	Branchlets, leaves, and calyces with different hairs than above.		(68)
63 (62)	Calyx teeth ca. 1/3 as long as calyx tube.		(64)
+	Calyx teeth ca. as long as calyx tube.		(66)
64 (63)	Leaves without a brown gland on lower surface of each tooth apex		29 Isodon rugosus
+	Leaves with a brown gland on lower surface of each tooth apex.		(65)
65 (64)	Panicles 8-20 cm		27 Isodon leucophyllus
+	Panicles 3-5 cm		28 Isodon adenolomus
66 (63)	Leaves 3-8 cm		30 Isodon grandifolius
+	Leaves less than 2.5 cm.		(67)
67 (66)	Leaf blade base rounded to shallowly cordate		31 Isodon oresbius
+	Leaf blade base cuneate to truncate-cuneate		32 Isodon dawoensis
68 (62)	Leaves conspicuously discolored.		(69)
+	Leaves not discolored.		(73)
69 (68)	Calyx teeth narrowly triangular or triangular-lanceolate.		(70)
+	Calyx teeth triangular to ovate-triangular.		(71)
70 (69)	Leaves ovate, 1.5-3.5 × 1-2.8 cm, margin crenate, adaxially dusty pubescent; petiole 5-13 mm		33 Isodon lihsienensis
+	Leaves lanceolate to oblanceolate, 0.8-1.5 × 0.5-0.7 cm, margin entire or obscurely few dentate above middle, adaxially densely tomentulose and papillate glandular; petiole 1-4 mm		34 Isodon wikstroemioides
71 (69)	Leaves 2.5-4.4 cm		35 Isodon smithianus
+	Leaves less than 2 cm.		(72)
72 (71)	Leaves oblong-ovate, ovate, to broadly ovate, adaxially glandular pubescent, margin coarsely crenate or entire, apex rounded; cymes widely spaced		36 Isodon parvifolius
+	Leaves lanceolate to ovate-lanceolate, adaxially densely pilose, margin remotely crenulate-serrulate above middle to entire, apex acute; cymes compact, in terminal panicles		37 Isodon tenuifolius
73 (68)	Cymes sessile or very short pedunculate; branchlets, inflorescences, and calyces densely hirtellous		38 Isodon hirtellus
+	Cymes conspicuously pedunculate; branchlets, inflorescences, and calyces not hirtellous.		(74)
74 (73)	Leaves and branchlets densely tomentose when young, subglabrescent with age		39 Isodon rubescens
+	Leaves and branchlets hairy.		(75)
75 (74)	Leaves ovate-lanceolate, 3.5-6(-10) × 1.5-2.5(-4) cm		40 Isodon loxothyrsus
+	Leaves ovate-oblong, rhomboid, to ovate-triangular, less than 4 cm.		(76)
76 (75)	Branchlets and petioles antrorsely dull yellow velutinuous-pubescent; leaves ovate-oblong, 1-2.5 × 0.5-1.4 cm, base rounded		41 Isodon xerophilus
+	Branchlets and petioles gray tomentulose; leaves rhombic to triangular-ovate, 1.5-4 × 1-2.5 cm, base broadly cuneate to truncate		42 Isodon rugosiformis