| 1 |
Scales on abaxial leaf surface all the same color. |
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(2) |
| + |
Scales on abaxial leaf surface with 2 different colors. |
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(22) |
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| 2 (1) |
Scales on abaxial leaf surface discontinuous, not overlapping. |
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(3) |
| + |
Scales on abaxial leaf surface contiguous or overlapping. |
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(7) |
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| 3 (2) |
Flowers yellow. |
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84 Rhododendron flavidum |
| + |
Flowers purple, pinkish-purple, violet, rose-lavender, lavender to purple-blue, rarely white. |
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(4) |
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| 4 (3) |
Erect shrubs; calyx lobes shorter than 2.5 mm. |
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87 Rhododendron polycladum |
| + |
Tufted shrubs; calyx lobes longer than 2.5 mm. |
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(5) |
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| 5 (4) |
Inflorescence 1- or 2-flowered; corolla 1.5–1.6 cm; petiole 3–5 mm. |
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112 Rhododendron lungchiense |
| + |
Inflorescence (1–)3(–5)-flowered; corolla (0.7–)0.8–1.5(–1.8) cm. |
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(6) |
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| 6 (5) |
Scales on abaxial leaf surface not opaque, fulvous or amber. |
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85 Rhododendron impeditum |
| + |
Scales on abaxial leaf surface opaque, white, pinkish or fawn-brown. |
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86 Rhododendron fastigiatum |
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| 7 (2) |
Scales on abaxial leaf surface dark. |
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(8) |
| + |
Scales on abaxial leaf surface pale. |
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(13) |
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| 8 (7) |
Calyx ca. 1 mm. |
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(9) |
| + |
Calyx (2–)3–4(–6) mm. |
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(10) |
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| 9 (8) |
Stamens and style usually included in corolla tube; corolla usually tubular-funnelform. |
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82 Rhododendron complexum |
| + |
Stamens and style usually exserted from corolla tube; corolla usually broadly funnelform. |
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83 Rhododendron tapetiforme |
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| 10 (8) |
Adaxial leaf surface green, densely lepidote, scales amber. |
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79 Rhododendron amundsenianum |
| + |
Adaxial leaf surface dark green, densely lepidote, scales pale. |
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(11) |
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| 11 (10) |
Leaves spaced along shoots; inflorescence 3–4(–6)-flowered. |
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80 Rhododendron yungningense |
| + |
Leaves mostly crowded at ends of shoots; inflorescence usually 2-flowered. |
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(12) |
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| 12 (11) |
Corolla 12–15(–20) mm, puberulous; stamens 10. |
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78 Rhododendron dasypetalum |
| + |
Corolla ca. 10 mm, glabrous outside; stamens 8. |
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81 Rhododendron qinghaiense |
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| 13 (7) |
Inflorescence usually 1–2-flowered. |
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(14) |
| + |
Inflorescence usually 2–10-flowered. |
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(18) |
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| 14 (13) |
Corolla 17–22 mm; calyx 5–7 mm. |
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74 Rhododendron dawuense |
| + |
Corolla 12–17(–19) mm; calyx 0.5–3 mm. |
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(15) |
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| 15 (14) |
Corolla 12–19 mm; calyx 2–3 mm. |
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(16) |
| + |
Corolla 5–11 mm; calyx 0.5–1.2 mm. |
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(17) |
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| 16 (15) |
Adaxial leaf surface pale green, matt, densely covered with overlapping scales; pedicels 1–5
mm; leaves usually narrowly elliptic to linear-lanceolate, 5–20 mm. |
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93 Rhododendron websterianum |
| + |
Adaxial surface dark green, shiny, covered with contiguous or nearly contiguous scales; pedicels 1–2 mm; leaves ovate to elliptic, (5–)7–10(–12) mm. |
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94 Rhododendron nitidulum |
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| 17 (15) |
Corolla 7–11 mm; stamens longer than corolla; adaxial leaf surface pale green, apex usually shortly mucronate. |
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105 Rhododendron thymifolium |
| + |
Corolla 5–6 mm; stamens shorter than corolla; adaxial leaf surface dark green, apex not mucronate. |
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106 Rhododendron yushuense |
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| 18 (13) |
Calyx usually 4–12 mm; corolla usually longer than 17 mm. |
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(19) |
| + |
Calyx usually 1–2 mm; corolla usually shorter than 17 mm. |
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(20) |
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| 19 (18) |
Plants robust, up to 1–2(–4) m tall; leaf blade 1–7 cm, apex mucronate; corolla usually pubescent outside; calyx usually reddish. |
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73 Rhododendron cuneatum |
| + |
Plants small, 0.5–0.6 m tall; leaf blade 0.7–1.4(–1.6) cm, apex not mucronulate; corolla glabrous
outside; calyx not reddish. |
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74 Rhododendron dawuense |
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| 20 (18) |
Leaf blade (8–)12–25(–40) mm; branchlets usually slender, fastigiate. |
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75 Rhododendron hippophaeoides |
| + |
Leaf blade 5–12(–20) mm; branchlets not fastigiate. |
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(21) |
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| 21 (20) |
Stamens usually 5, exserted from corolla tube, filaments glabrous. |
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76 Rhododendron tsaii |
| + |
Stamens usually 10, not exserted from corolla tube, filaments pubescent towards base. |
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77 Rhododendron intricatum |
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| 22 (1) |
Scales on abaxial leaf surface usually golden to yellow-brown, with a few darker scales intermixed. |
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(23) |
| + |
Scales on abaxial leaf surface usually with pale and darker scales nearly equal in number and intermixed. |
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(26) |
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| 23 (22) |
Calyx 4–7.5 mm. |
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95 Rhododendron minyaense |
| + |
Calyx shorter than 4 mm. |
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(24) |
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| 24 (23) |
Erect shrubs; calyx 0.5–1.5 mm. |
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107 Rhododendron orthocladum |
| + |
Straggling or prostrate shrubs; calyx 0.5–4 mm. |
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(25) |
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| 25 (24) |
Leaves 12–21 mm, apex usually emarginate. |
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108 Rhododendron bulu |
| + |
Leaves 3–12 mm, apex strongly mucronate. |
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109 Rhododendron telmateium |
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| 26 (22) |
Young shoots densely conspicuously loriform-setose. |
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88 Rhododendron setosum |
| + |
Young shoots never loriform-setose. |
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(27) |
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| 27 (26) |
Inflorescence usually 3–5(–15)-flowered; style long. |
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(28) |
| + |
Inflorescence usually 1–4-flowered; style short. |
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(31) |
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| 28 (27) |
Calyx 1–2 mm. |
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92 Rhododendron lapponicum |
| + |
Calyx 2.5–6 mm. |
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(29) |
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| 29 (28) |
Corolla scaly outside. |
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90 Rhododendron rupicola |
| + |
Corolla not scaly outside. |
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(30) |
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| 30 (29) |
Leaf blade 16–40(–65) mm, apex shortly mucronate; corolla tube 4–9 mm. |
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89 Rhododendron russatum |
| + |
Leaf blade 7–18(–24) mm, apex rounded, not mucronate; corolla tube 3–5 mm. |
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91 Rhododendron capitatum |
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| 31 (27) |
Inflorescence usually 2–4-flowered. |
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(32) |
| + |
Inflorescence 1–2(–3)-flowered. |
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(34) |
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| 32 (31) |
Calyx 2.5–3.5 mm, lobes oblong; leaf blade 8–14 mm. |
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96 Rhododendron labolengense |
| + |
Calyx 0.8–1.5 mm, lobes orbicular or broadly triangular; leaf blade 10–20 mm. |
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(33) |
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| 33 (32) |
Small shrubs, 0.3–0.4 m tall; leaf apex mucronate; calyx not scaly outside; style ca. 8 mm. |
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102 Rhododendron declivatum |
| + |
Shrubs up to 1 m tall; leaf apex rounded, not mucronate; calyx scaly outside; style to 11 mm. |
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110 Rhododendron joniense |
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| 34 (31) |
Inflorescence only 1-flowered. |
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(35) |
| + |
Inflorescence (1–)2(–3)-flowered. |
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(37) |
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| 35 (34) |
Corolla yellow; plants 2–4 m tall. |
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111 Rhododendron maowenense |
| + |
Corolla blue; plants 0.5–1(–1.5) m tall. |
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(36) |
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| 36 (35) |
Calyx ca. 4.5 mm, lobes oblong; leaf blade 5–12 mm; corolla ca. 12 mm. |
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98 Rhododendron zheguense |
| + |
Calyx ca. 0.5 mm, lobes triangular; leaf blade 4–6 mm; corolla 4–5 mm. |
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99 Rhododendron bamaense |
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| 37 (34) |
Low, prostrate shrubs, usually forming cushions. |
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(38) |
| + |
Erect shrubs. |
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(39) |
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| 38 (37) |
Leaf blade 10–25 mm, apex mucronate; scales on adaxial leaf surface rubbing off, ruby red, shiny; corolla glabrous outside. |
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103 Rhododendron taibaiense |
| + |
Leaf blade 3.5–9(–12) mm, apex usually not mucronate; scales on adaxial leaf surface pale to golden; corolla usually pubescent outside. |
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104 Rhododendron nivale |
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| 39 (37) |
Calyx 4–6 mm; scales on adaxial leaf surface pale; corolla ca. 15 mm. |
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97 Rhododendron xiguense |
| + |
Calyx 2–3 mm; scales on adaxial leaf surface yellowish to golden; corolla 10–13 mm. |
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(40) |
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| 40 (39) |
Leaves 15–20 mm; calyx ca. 3 mm, not scaly outside, lobe margin not ciliate. |
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101 Rhododendron gologense |
| + |
Leaves 8–15 mm; calyx ca. 2 mm, scaly outside, lobe margin ciliate. |
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100 Rhododendron zekoense |
