1	Roots swollen, fusiform, tuberous; plants densely tufted with small growing point.		(2)
+	Roots not tuberous; plants with rhizomes (sometimes very short).		(4)
2 (1)	Flowers dark violet, crest of outer perianth segments deeply fimbriate; plants stemless		33 Iris barbatula
+	Flowers pale violet, crest of outer perianth segments not deeply fimbriate; plants with or without stem.		(3)
3 (2)	Flowering stems sometimes branched, more than 10 cm; perianth tube 2.5--3 cm		31 Iris decora
+	Flowering stems always simple, very short (to 8 cm), or not emerging from ground; perianth tube 3--5 cm		32 Iris collettii
4 (1)	Flowering stems dichotomously branched; pedicels of fallen flowers persistent, exserted from spathes, stiff; outer perianth segments not crested.		(5)
+	Flowering stems not or not obviously dichotomously branched; if pedicels of fallen flowers persistent and exserted, then outer perianth segments crested.		(6)
5 (4)	Flowering stems bearing well-developed, falcate leaves; perianth tube extremely short		35 Iris dichotoma
+	Flowering stems bearing reduced leaves, leaves of basal fans erect or slightly incurved; perianth tube ca. 2 cm		36 Iris subdichotoma
6 (4)	Outer perianth segments with a toothed crest or beard of clavate hairs.		(7)
+	Outer perianth segments without a beard or crest.		(29)
7 (6)	Outer perianth segments with a crest.		(8)
+	Outer perianth segments with a beard of clavate hairs.		(16)
8 (7)	Plants with leafy stems; leaves alternate on stem or clustered into a terminal fan.		(9)
+	Plants with leaves in basal fans or tufts.		(11)
9 (8)	Leaves alternate on stem, not clustered into a terminal fan; flowers pale reddish purple		42 Iris milesii
+	Leaves clustered into a terminal fan; flowers violet, pale blue, or white.		(10)
10 (9)	Flowers pale blue or white, 4--5.5 cm in diam.		39 Iris confusa
+	Flowers violet, 7.5--8 cm in diam.		40 Iris wattii
11 (8)	Flowering stems with at least 4 lateral branches.		(12)
+	Flowering stems simple or with 1 or 2 lateral branches.		(13)
12 (11)	Flowering stems with 5--12 branches; flowers 4.5--5.5 cm in diam.		37 Iris japonica
+	Flowering stems with 4 or 5 branches; flowers 7--8 cm in diam.		38 Iris formosana
13 (11)	Rhizomes not obvious; roots thick; style branches ca. 1.5 cm wide, terminal lobes incurved toward center of flower		34 Iris latistyla
+	Rhizomes obvious; roots slender; style branches narrower, terminal lobes not incurved toward center of flower.		(14)
14 (13)	Rhizomes ca. 1 cm in diam.; leaves 1.5--3.5 cm wide; flowers ca. 10 cm in diam.; crest of outer perianth segments white, irregularly toothed		41 Iris tectorum
+	Rhizomes less than 1 cm in diam.; leaves less than 1.5 cm wide; flowers less than 6 cm in diam.; crest of outer perianth segments yellow, low.		(15)
15 (14)	Leaves 6--12 mm wide; rhizomes not filiform; capsule held at right angle to pedicel		43 Iris speculatrix
+	Leaves 1--7 mm wide; rhizomes filiform; capsule erect		44 Iris proantha
16 (7)	Plants surrounded by dense, fibrous remains of old leaf bases.		(17)
+	Plants usually without dense, fibrous remains of old leaf bases.		(20)
17 (16)	Fibers strongly twisted and coiled		52 Iris potaninii
+	Fibers ± straight.		(18)
18 (17)	Rhizomes swollen, tuberlike; spathes 2-flowered; flowering stems to 35 cm; flowers ca. 6 cm in diam.		51 Iris leptophylla
+	Rhizomes neither swollen nor tuberlike; spathes 1-flowered; plants stemless or with flowering stems to 20 cm; flowers to 5 cm in diam.		(19)
19 (18)	Flowers yellow		53 Iris psammocola
+	Flowers violet or purple		54 Iris tigridia
20 (16)	Flowers yellow.		(21)
+	Flowers violet-purple.		(25)
21 (20)	Flowers ± flat, all parts spreading		49 Iris narcissiflora
+	Flowers not flat, inner perianth segments ± erect.		(22)
22 (21)	Leaves with swollen basal sheaths		48 Iris curvifolia
+	Leaves without swollen basal sheaths.		(23)
23 (22)	Rhizomes creeping		45 Iris flavissima
+	Rhizomes compact.		(24)
24 (23)	Spathes red flushed		46 Iris bloudowii
+	Spathes green		47 Iris mandshurica
25 (20)	Leaves glaucous, falcate, more than 1 cm wide		50 Iris scariosa
+	Leaves not as above, often poorly developed at anthesis.		(26)
26 (25)	Flowering stems developed.		(27)
+	Flowering stems not developed.		(28)
27 (26)	Flowers small, to 3 cm in diam., inner perianth segments spreading		55 Iris goniocarpa
+	Flowers large, 6--7 cm in diam., inner perianth segments erect		56 Iris cuniculiformis
28 (26)	Flowers pale to mauve-purple, blotched darker, perianth tube 5.5--6 cm, inner segments erect		57 Iris kemaonensis
+	Flowers dark violet, obscurely mottled, perianth tube 4--14 cm, inner segments spreading		58 Iris dolichosiphon
29 (6)	Flowers subtended by a single bract		13 Iris anguifuga
+	Flowers subtended by 2 or more bracts (spathes).		(30)
30 (29)	Rhizomes short; plants densely tufted, tufts surrounded by a tough collar of old leaf sheaths.		(31)
+	Rhizomes elongate; stems and leaf bases usually without a tough collar of old leaf sheaths.		(39)
31 (30)	Spathes ovate, inflated.		(32)
+	Spathes ± lanceolate, not inflated		(33)
32 (31)	Spathes with transverse veins		23 Iris ventricosa
+	Spathes without transverse veins		22 Iris bungei
33 (31)	Flowering stems obvious, emerging above ground.		(34)
+	Flowering stems not emerging above ground.		(35)
34 (33)	Flowers flat, outer and inner perianth segments spreading		24 Iris farreri
+	Flowers funnelform, outer perianth segments ascending		25 Iris songarica
35 (33)	Flowers yellow with dark violet markings, 3--5 cm in diam.		30 Iris kobayashii
+	Flowers violet or blue.		(36)
36 (35)	Outer perianth segments very narrow, to 0.8 cm wide.		(37)
+	Outer perianth segments more than 1 cm wide.		(38)
37 (36)	Flowers to 5 cm in diam. (Qinghai)		27 Iris qinghainica
+	Flowers more than 6 cm in diam. (E China)		29 Iris cathayensis
38 (36)	Leaves ca. 2 mm wide; perianth tube to 8 cm		26 Iris tenuifolia
+	Leaves ca. 3 mm wide; perianth tube to 14 cm		28 Iris loczyi
39 (30)	Flowers yellow or whitish.		(40)
+	Flowers purplish, bluish, or violet.		(46)
40 (39)	Plants small; rhizomes long, slender.		(41)
+	Plants robust; rhizomes stout.		(42)
41 (40)	Flowers yellow		14 Iris minutoaurea
+	Flowers white, with yellow signal patch on limb of outer perianth segments		15 Iris odaesanensis
42 (40)	Ovary long and slender, apex beaklike.		(43)
+	Ovary short and thick.		(44)
43 (42)	Outer perianth segments with expanded limb, abruptly contracted into narrow claw		20 Iris halophila
+	Outer perianth segments oblanceolate, gradually narrowed toward base		21 Iris lactea
44 (42)	Flowering stems with several branches; leaves usually more than 1 cm wide (NE China)		8 Iris maackii
+	Flowering stems simple; leaves less than 1 cm wide (SW China).		(45)
45 (44)	Inner perianth segments erect; leaves glossy on 1 surface, dull on other; flanges of claw of outer perianth segments inconspicuous		2 Iris forrestii
+	Inner perianth segments spreading obliquely; leaves dull on both surfaces; flanges of claw of outer perianth segments conspicuous, purple mottled		1 Iris wilsonii
46 (39)	Plants stemless or with slender flowering stems to 25 cm; flowers to 5.5 cm in diam.		(47)
+	Plants with stout flowering stems usually more than 25 cm; flowers usually more than 5.5 cm in diam.		(50)
47 (46)	Pedicels slender, 2--4 cm, exserted from spathes; spathes several flowered		17 Iris henryi
+	Pedicels to 1 cm, not exserted from spathes; spathes 1-flowered.		(48)
48 (47)	Perianth tube 5--7 cm		16 Iris rossii
+	Perianth tube less than 1.5 cm.		(49)
49 (48)	Spathes green, lanceolate, soft, membranous, apex finely acuminate		18 Iris ruthenica
+	Spathes yellowish green, broadly lanceolate, hard, dry, membranous, apex obtuse or subacute		19 Iris uniflora
50 (46)	Inner perianth segments much reduced		12 Iris setosa
+	Inner perianth segments conspicuous.		(51)
51 (50)	Leaves with obvious midvein.		(52)
+	Leaves without obvious midvein.		(53)
52 (51)	Leaves narrowly linear, ca. 2 mm wide; spathes membranous, parallel veins not obvious		10 Iris typhifolia
+	Leaves linear, 5--12 mm wide; spathes leathery, parallel veins obvious		11 Iris ensata
53 (51)	Ovary long and slender, apex beaklike; perianth tube less than 1 cm.		(54)
+	Ovary short and wide; perianth tube more than 1 cm.		(55)
54 (53)	Outer perianth segments with expanded limb, abruptly contracted into narrow claw		20 Iris halophila
+	Outer perianth segments oblanceolate, gradually narrowed toward base		21 Iris lactea
55 (53)	Flowering stems solid		6 Iris clarkei
+	Flowering stems hollow.		(56)
56 (55)	Claw of outer perianth segments with reticulate pattern (NE China)		7 Iris sanguinea
+	Claw of outer perianth segments without reticulate pattern (mainly SW China).		(57)
57 (56)	Flowers more than 9 cm in diam.; spathes short and broad, very unequal, apex acute or obtuse; stigma flap 2-lobed (NE China and cultivated)		9 Iris laevigata
+	Flowers to 9 cm in diam.; spathes long and narrow, subequal, apex very acute; stigma flap triangular (SW China).		(58)
58 (57)	Plants usually more than 70 cm; flowering stems usually branched		5 Iris delavayi
+	Plants less than 70 cm; flowering stems simple.		(59)
59 (58)	Flowers dark violet, limb of outer perianth segments with gold markings at base		3 Iris chrysographes
+	Flowers paler, bluish to violet, limb of outer perianth segments with white or yellow-tinged patch at center marked with darker veins		4 Iris bulleyana