1	Stamens (6–)7–10.		(2)
+	Stamens (4–)5(–6).		(22)
2 (1)	Style with hairs at base.		(3)
+	Style glabrous.		(8)
3 (2)	Stamens exserted from corolla.		(4)
+	Stamens shorter than corolla.		(5)
4 (3)	Leaf blade broadest below middle, 0.5–1.9 cm wide; calyx lobes coarsely yellowish brown silky strigose.		497 Rhododendron rubropilosum
+	Leaf blade broadest above middle, 2–3 cm wide; calyx lobes sparsely pubescent.		499 Rhododendron lasiostylum
5 (3)	Leaf blade linear-lanceolate or linear-oblanceolate to obovate; stamens 10; corolla crimson to dark red, 3.5–4 cm, lobes ovate or long-ovate.		494 Rhododendron kanehirae
+	Leaf blade oblong to oblong-obovate or elliptic to elliptic-ovate; stamens (5–)6–10; corolla pink or purplish, 1–3.2 cm.		(6)
6 (5)	Corolla 1–1.5(–2) cm; stamens 9 or 10.		505 Rhododendron taiwanalpinum
+	Corolla 3–3.2 cm; stamens (5–)6–10.		(7)
7 (6)	Young shoots gray-white silky strigose; abaxial leaf surface coarsely brown-strigose; stamens 7.		495 Rhododendron tenuilaminare
+	Young shoots blackish-brown-strigose; abaxial leaf surface densely ferruginous-silky-strigose; stamens (5–)6–10.		496 Rhododendron strigosum
8 (2)	Leaf blade 0.7–1.8 cm; corolla ca. 1.5 cm.		503 Rhododendron noriakianum
+	Leaf blade 2–7(–8); corolla 2.2–5.2 cm.		(9)
9 (8)	Stamens shorter than or as long as the corolla.		(10)
+	All stamens as long as or longer than corolla.		(16)
10 (9)	Stamens 7–10, some as long as the corolla; corolla 1.8–2.8 cm.		(11)
+	Stamens 10, shorter than corolla; corolla 3–5.2 cm.		(12)
11 (10)	Corolla ca. 2.8 cm; inflorescence 4–6-flowered; leaf blade with lateral veins 4–5-paired.		507 Rhododendron subflumineum
+	Corolla 1.8–2 cm; inflorescence 2–4-flowered; leaf blade with lateral veins ca. 3-paired.		508 Rhododendron linguiense
12 (10)	Calyx lobes 2–2.5 mm; corolla 3–3.5 cm.		(13)
+	Calyx lobes 3–12 mm; corolla 4–5.2 cm.		(14)
13 (12)	Leaf blade ovate to ovate-oblong, or oblong-lanceolate; calyx triangular-ovate, ca. 2.5 mm; corolla ca. 3 cm, lobes oblong; stamens slightly shorter than corolla.		501 Rhododendron longiperulatum
+	Leaf blade ovate to oblong or oblanceolate to broad-elliptic; calyx lobes broadly elliptic to ovate, ca. 2 mm; corolla ca. 3.5 cm, lobes obovate; stamens half as long as corolla.		502 Rhododendron nakaharae
14 (12)	Leaf blade linear-lanceolate to narrowly lanceolate, 0.3–1.1 cm wide; pedicel densely brown strigose.		500 Rhododendron hainanense
+	Leaf blade ovate to oblong, ovate-oblong or oblong-lanceolate, 1–5 cm wide; pedicel yellowish brown villous or glandular setose.		(15)
15 (14)	Young shoots and leaves with spreading flat and red-brown glandular hairs, also pubescent; calyx lobes triangular-ovate to ovate-lanceolate, 3–8 mm; corolla 4–4.8 cm.		504 Rhododendron oldhamii
+	Young shoots and leaves with coarse appressed hairs; calyx lobes lanceolate, ca. 12 mm; corolla 4.8–5.2 cm.		506 Rhododendron x pulchrum
16 (9)	Stamens as long as corolla.		(17)
+	Stamens longer than corolla.		(19)
17 (16)	Corolla reddish, yellowish when dried, without purple flecks; stamens 8.		511 Rhododendron octandrum
+	Corolla red, rose or pink with dark red flecks, 2.2–4 cm; stamens 10.		(18)
18 (17)	Corolla ca. 2.2 cm, dark purple-red to pink, lobes oblong.		509 Rhododendron atrovirens
+	Corolla 3.5–4 cm, scarlet red, lobes obovate.		510 Rhododendron simsii
19 (16)	Corolla white, 3–4.5 cm; calyx lobes ca. 12 mm, with glandular hairs; young shoots densely villous, mixed with fewer glandular hairs.		512 Rhododendron mucronatum
+	Corolla dark red, purple or dark blue, 2.2–3 cm; calyx lobes to 3.5 mm; young shoots variously hairy but not glandular.		(20)
20 (19)	Corolla dark blue, 2.2–2.5 cm; young shoots with appressed hairs.		513 Rhododendron longifalcatum
+	Corolla dark red or purple, 2.5–3 cm; young shoots with spreading or crisped hairs.		(21)
21 (20)	Corolla dark red; young shoots densely red-brown short-setose and sparsely spreading long-hairy; stamens partly exserted.		514 Rhododendron rufohirtum
+	Corolla purple; young shoots densely yellowish brown crisped villous; stamens conspicuously exserted.		515 Rhododendron pulchroides
22 (1)	Young shoots with gland-tipped hairs or setae, often also with non-glandular hairs.		(23)
+	Young shoots with non-glandular hairs or bristles only.		(33)
23 (22)	Style glandular.		(24)
+	Style glabrous.		(28)
24 (23)	Corolla 1.2–1.9 cm, glabrous within; style 2.4–2.8 cm.		(25)
+	Corolla 1–1.2 cm, puberulous within; style 1.2–2 cm.		(26)
25 (24)	Leaf blade 10–18(–20) cm; inflorescence 10–15-flowered; corolla red, 1.2–1.4 cm.		560 Rhododendron yaoshanicum
+	Leaf blade 2.5–7(–10) cm; inflorescence 5–6-flowered; corolla purple-red, 1.7–1.9 cm.		564 Rhododendron jinxiuense
26 (24)	Inflorescence 5–12-flowered; style 1.8–2 cm, longer than stamens.		559 Rhododendron jinpingense
+	Inflorescence 3–5-flowered; style ca. 1.2 cm, shorter than or as long as stamens.		(27)
27 (26)	Young shoots, petiole and pedicel with long-setae and short glandular hairs; petiole 4–10 mm; pedicel 8–10 mm.		541 Rhododendron rhuyuenense
+	Young shoots, petiole and pedicel setose-strigose; petiole ca. 3 mm; pedicel 5–7 mm.		545 Rhododendron hunanense
28 (23)	Corolla red, 1.2–1.8 cm.		519 Rhododendron taipaoense
+	Corolla purple-red, pale purple, pink or white, 1.8–2.5 cm.		(29)
29 (28)	Young shoots with eglandular setae to 4 mm as well as short gland-tipped hairs; calyx lobes with long ferruginous setae on the margin; inflorescence 8–9(–16)-flowered.		528 Rhododendron kwangtungense
+	Young shoots with eglandular setae short or absent; calyx strigose or with dense short brown bristles; inflorescence 10–18-flowered.		(30)
30 (29)	Abaxial leaf surface densely yellow-brown woolly and ferruginous strigose; corolla ca. 2.5 cm.		525 Rhododendron florulentum
+	Abaxial leaf surface with short brown or red-brown bristles only; corolla 1.8–2.3 cm.		(31)
31 (30)	Pedicel and calyx with both short gland-tipped hairs and coarse appressed hairs, pedicel ca. 1.5 cm; filaments puberulent at base.		529 Rhododendron rivulare
+	Pedicel without glandular hairs; pedicel 0.8–1 cm; filaments glabrous.		(32)
32 (31)	Leaf blade 4.5–8(–9.5) × 2.5–4.5 cm; pedicel brown silky strigose; inflorescence 10–12-flowered.		524 Rhododendron jasminoides
+	Leaf blade 2–5(–10) × 1–2(–5) cm; pedicel with short red-brown bristles; inflorescence to 18-flowered.		527 Rhododendron apricum
33 (22)	Style glabrous.		(34)
+	Style strigose or less often pubescent towards base.		(50)
34 (33)	Corolla 2.4–4 cm; style 3.5–5 cm.		(35)
+	Corolla 1.2–2.2(–2.5) cm; style 1–2.8 cm.		(38)
35 (34)	Corolla bright red, occasionally rose-red, 3–4 cm; pedicel and calyx hairs white.		530 Rhododendron indicum
+	Corolla white to pale pink or purple, or purple-red, 2.4–3.1 cm; pedicel and calyx hairs yellow-brown or ferruginous.		(36)
36 (35)	Petiole 1–2 mm; pedicel ca. 7 mm.		532 Rhododendron naamkwanense
+	Petiole 3–5 mm; pedicel 9–18 mm.		(37)
37 (36)	Style ca. 5 cm, longer than stamens.		531 Rhododendron chrysocalyx
+	Style ca. 3.5 cm, as long as stamens.		523 Rhododendron meridionale
38 (34)	Young shoots with crisped hairs; corolla white, yellowish when dried, upper lobes with rose flecks.		563 Rhododendron saxatile
+	Young shoots with strigose indumentum only; corolla red to pink, purple-red or pale purple, or lilac (corolla color not recorded for R. crassimedium).		(39)
39 (38)	Stamens 4–6; pedicel ca. 10 mm; inflorescence 2- or 3-flowered.		498 Rhododendron sikayotaizanense
+	Stamens 5; pedicel 4–7(–10) mm; inflorescence sometimes more than 3-flowered.		(40)
40 (39)	Style 2.4–2.8 cm.		(41)
+	Style 1–2 cm.		(44)
41 (40)	Inflorescence usually 2- or 3-flowered; petiole ca. 2 mm; leaf blade membranous.		536 Rhododendron obtusum
+	Inflorescence 5–16-flowered; petiole 3–12 mm; leaf blade leathery.		(42)
42 (41)	Stamens ca. 3 cm; leaf with gray-white hairs.		520 Rhododendron litchiifolium
+	Stamens 1.7–2.7 cm; leaf with brown or reddish brown hairs.		(43)
43 (42)	Leaf blade leathery, 3–7.8(–11) × 1.3–4 cm, elliptic-lanceolate to elliptic-obovate; corolla lilac, lobes oblong-lanceolate, apex acute.		533 Rhododendron mariae
+	Leaf blade papery, 1.5–3.6 × 1–2 cm, lanceolate or oblong-lanceolate; corolla purple-red or purplish, lobes long-lanceolate, apex mucronate.		534 Rhododendron kwangsiense
44 (40)	Pedicel 6–10 mm; calyx ca. 6 mm.		(45)
+	Pedicel 3–4 mm.		(47)
45 (44)	Leaf blade 1.3–1.5 cm, adaxial surface with dense fine warts, sparsely pubescent; stamen filaments glabrous.		517 Rhododendron crassimedium
+	Leaf blade 1.8–3.5 cm, adaxial surface without warts, hairs appressed; stamen filaments puberulent or pubescent below.		(46)
46 (45)	Stamens 0.9–1.1 cm; corolla with dark spots.		516 Rhododendron hypoblematosum
+	Stamens 2.2–2.7 cm; corolla not marked.		522 Rhododendron nanpingense
47 (44)	Leaf blade papery; corolla ca. 2 cm.		535 Rhododendron microphyton
+	Leaf blade leathery; corolla 1–1.6 cm.		(48)
48 (47)	Leaf blade apex obtuse or subrounded, often mucronate; inflorescence 3–5-flowered.		518 Rhododendron tingwuense
+	Leaf blade apex acute or shortly acuminate; inflorescence 5–12-flowered.		(49)
49 (48)	Corolla ca. 1 cm; stamens ca. 1 cm, filaments puberulous below.		543 Rhododendron tsoi
+	Corolla 1.2–1.3 cm; stamens 1.3–1.7 cm, filaments glabrous.		526 Rhododendron unciferum
50 (33)	Filaments glabrous.		(51)
+	Filaments partly pubescent or puberulous.		(59)
51 (50)	Corolla ca. 2.5 cm; pedicel densely long-setose.		552 Rhododendron breviperulatum
+	Corolla 1–2.2 cm; pedicel strigose, sometimes also with crisped hairs.		(52)
52 (51)	Young shoots with crisped hairs; corolla white, yellowish when dried.		563 Rhododendron saxatile
+	Young shoots with strigose indumentum only; corolla white, purple or pale red.		(53)
53 (52)	Corolla purple or purplish.		(54)
+	Corolla white to pale red.		(56)
54 (53)	Corolla purple, without markings; inflorescence 2–3-flowered.		546 Rhododendron myrsinifolium
+	Corolla purplish, with purple flecks; inflorescence 5–10(–13)-flowered.		(55)
55 (54)	Corolla outer surface with glandular hairs; leaf blade papery, adaxial surface without prominences.		558 Rhododendron qianyangense
+	Corolla outer surface glabrous; leaf blade leathery, adaxial surface with mammiform prominences.		542 Rhododendron crassistylum
56 (53)	Leaf blade 6–7 cm; shrubs or small trees 3–4 m tall; stamens subequal, ca. 1 cm.		561 Rhododendron flosculum
+	Leaf blade 1–6 cm; small shub 1–2 m tall; stamens unequal, 1.2–2.3 cm.		(57)
57 (56)	Petiole 6–13 mm; corolla ca. 2.2 cm.		557 Rhododendron seniavinii
+	Petiole 2–4 mm; corolla 1.1–1.6 cm.		(58)
58 (57)	Young shoots gray-white strigose, glabrescent; corolla ca. 1.6 cm; stamens 1.6–2.3 cm .		550 Rhododendron cretaceum
+	Young shoots reddish strigose; corolla ca. 1.1 cm; stamens 1.3–1.6 cm.		538 Rhododendron hejiangense
59 (50)	Corolla 2.3–3.5 cm.		(60)
+	Corolla 0.6–2 cm.		(63)
60 (59)	Inflorescence 1- or 2-flowered; corolla ca. 2.3 cm.		556 Rhododendron rhodanthum
+	Inflorescence 3–10-flowered; corolla 2.5–3.5 cm.		(61)
61 (60)	Inflorescence ca. 10-flowered; young shoots sparsely spreading pubescent and coarsely strigose.		565 Rhododendron spadiceum
+	Inflorescence 3–6-flowered; young shoots strigose.		(62)
62 (61)	Leaf blade 2–3 cm, apex obtuse; corolla ca. 2.5 cm, rose-pink with crimson flecks on upper lobes.		552 Rhododendron breviperulatum
+	Leaf blade 3–5.5 cm, apex acuminate; corolla ca. 3.5 cm, reddish purple.		568 Rhododendron loniceriflorum
63 (59)	Corolla 1.5–2 cm.		(64)
+	Corolla 0.6–1.3 cm.		(67)
64 (63)	Pedicel ca. 15 mm, setose; petiole glabrous.		562 Rhododendron sparsifolium
+	Pedicel 5–7(–11) mm, strigose; petiole strigose.		(65)
65 (64)	Abaxial leaf surface with hairs only on the midrib and lateral vein; inflorescence 3- or 4-flowered; pedicel ca. 5 mm.		549 Rhododendron malipoense
+	Abaxial leaf surface more uniformly sparsely strigose; inflorescence usually 4–7-flowered; pedicel 5–10 mm.		(66)
66 (65)	Leaf blade widest at or below middle, base subrounded; petiole 5–7(–10) mm.		566 Rhododendron flumineum
+	Leaf blade widest above middle, rarely narrow-elliptic, base cuneate or broadly cuneate; petiole 3–5 mm.		567 Rhododendron subcerinum
67 (63)	Style with glandular hairs.		(68)
+	Style without glandular hairs.		(72)
68 (67)	Corolla rotate-funnelform, ca. 6 mm, outside surface with red glands.		554 Rhododendron minutiflorum
+	Corolla funnelform to funnel-campanulate, 8–13 mm, outside surface with glands not red.		(69)
69 (68)	Stamens subequal, 8–14 mm; style 15–18 mm.		555 Rhododendron chunii
+	Stamens unequal, 12–16 mm; style 12–15 mm.		(70)
70 (69)	Leaf blade leathery, margin red-brown strigose, apex obtusely pointed; pedicel 6–8 mm.		548 Rhododendron subenerve
+	Leaf blade papery, margin not strigose, sometimes ciliate, apex acuminate; pedicel 4–5 mm.		(71)
71 (70)	Petiole and pedicel strigose; style sparsely glandular hairy below.		539 Rhododendron fuchsiifolium
+	Petiole and pedicel spreading setose, pedicel also glandular; style strigose below, shortly stipitate-glandular above.		547 Rhododendron guizhongense
72 (67)	Style 1.7–2 cm.		(73)
+	Style 1–1.3 cm.		(74)
73 (72)	Corolla 1.2–1.4 cm, outer surface without projections.		521 Rhododendron polyraphidoideum
+	Corolla ca. 0.9 cm, outer surface with small obtuse spines.		553 Rhododendron viscigemmatum
74 (72)	Inflorescence 2- or 3-flowered.		569 Rhododendron tenue
+	Inflorescence 4–8(–9)-flowered.		(75)
75 (74)	Leaf blade papery, apex not mucronate; pedicel 3–4 mm.		(76)
+	Leaf blade leathery, apex mucronate; pedicel 4–7 mm.		(77)
76 (75)	Corolla pink; style strigose to apex.		544 Rhododendron fuscipilum
+	Corolla white; style glabrous towards apex.		537 Rhododendron adenanthum
77 (75)	Corolla without spots, both surfaces glabrous; style longer than shorter stamens.		540 Rhododendron viscidum
+	Corolla with upper 3 lobes with dark red flecks, both surfaces hairy; style shorter than all stamens.		551 Rhododendron yangmingshanense