| 1 |
Leaf blade ± hairy on both sides, or at least midrib pubescent or hispid abaxially and pubescent adaxially. |
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(2) |
| + |
Leaf blade glabrous on both surfaces, or at most pubescent along midrib adaxially. |
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(7) |
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| 2 (1) |
Corolla pale yellow; abaxial leaf surface with scales 3–5 × their own diameter apart. |
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44 Rhododendron shimianense |
| + |
Corolla white, pale green, purple or rosy red; abaxial leaf surface densely or sparsely scaly. |
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(3) |
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| 3 (2) |
Young shoots, petiole, leaf adaxial surface, corolla tube, and ovary hispid. |
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45 Rhododendron trichanthum |
| + |
Young shoots, petiole, leaf adaxial surface, corolla tube, and ovary pubescent or glabrous, not hispid. |
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(4) |
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| 4 (3) |
Corolla 1.5–2 cm. |
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(5) |
| + |
Corolla 2.5–3.5 cm. |
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(6) |
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| 5 (4) |
Leaf obovate or elliptic; apex obtuse or rounded; corolla rosy red; leaf abaxial surface densely scaly,
scales at most 1 × their own diameter apart; pedicel 7–10 mm. |
|
46 Rhododendron bivelatum |
| + |
Leaf ovate; apex apiculate; corolla white; leaf abaxial surface sparsely scaly, scales 1–3 × their
own diameter apart; pedicel 3–6 mm. |
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47 Rhododendron guangnanense |
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| 6 (4) |
Leaf blade 3–7 cm; corolla purple, red, or white. |
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48 Rhododendron augustinii |
| + |
Leaf blade 7–10 cm; corolla pale green. |
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49 Rhododendron brachypodum |
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| 7 (1) |
Corolla yellow, creamy yellow or pale green. |
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(8) |
| + |
Corolla white, pale red or purple, never yellow. |
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(11) |
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| 8 (7) |
Leaf blade papery, abaxial surface sparsely scaly, scales 0.5–6 × their own diameter apart; leaf apex acuminate or caudate; corolla densely pubescent outside. |
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50 Rhododendron lutescens |
| + |
Leaf blade leathery, abaxial surface densely scaly, scales ± contiguous to their own diameter apart; leaf apex acute, acuminate or obtuse; corolla glabrous or pubescent outside. |
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(9) |
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| 9 (8) |
Corolla outer surface not scaly, 1.6–2.2 cm. |
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51 Rhododendron wongii |
| + |
Corolla outer surface scaly, 2–3.5 cm. |
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(10) |
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| 10 (9) |
Corolla with yellowish green markings inside; scales on abaxial leaf surface dimorphic, the larger
deep brown, the smaller yellowish brown; leaf midrib adaxially hairy. |
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52 Rhododendron ambiguum |
| + |
Corolla with brown spots inside; scales on abaxial leaf surface uniform; leaf midrib adaxially
glabrous. |
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53 Rhododendron triflorum |
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| 11 (7) |
Scales on abaxial leaf surface scattered, (1–)2–4(–8) × their own diameter apart. |
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(12) |
| + |
Scales on abaxial leaf surface dense, ± contiguous to 1 × their own diameter apart. |
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(15) |
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| 12 (11) |
Mature leaves with abaxial surface pinkish white, scales 0.5–4 × their own diameter apart; corolla white to lavender pink, densely glandular-scaly outside, sometimes pubescent on tube. |
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54 Rhododendron zaleucum |
| + |
Mature leaves with abaxial surface pale green or pale brown; corolla pale red, pale purple or white,
sparsely scaly or not outside, without hairs. |
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(13) |
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| 13 (12) |
Leaf blade V-shaped in cross section; scales on abaxial surface contiguous to 4 × their own diameter apart; adaxial surface and petioles glabrous. |
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55 Rhododendron davidsonianum |
| + |
Leaf blade flat; scales on abaxial surface 2–8 × their own diameter apart; adaxial surface and
petioles sometimes hairy. |
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(14) |
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| 14 (13) |
Evergreen; young shoots, leaf adaxially along midrib, leaf margin and petioles glabrous or pubescent; corolla pale purple in bud. |
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56 Rhododendron rigidum |
| + |
Evergreen or semievergreen; young shoots, leaf adaxial surface, leaf margin and petioles glabrous or pubescent or sparsely hispid; corolla white in bud (see also 58. R. pleistanthum) |
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57 Rhododendron yunnanense |
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| 15 (11) |
Leaves 1.6–2.6 × 0.5–1.2 cm; corolla 1.3–1.6 cm, not scaly outside. |
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59 Rhododendron gemmiferum |
| + |
Leaves 2–11 × 1–3.5 cm; corolla 1.5–4 cm, scaly or not outside. |
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(16) |
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| 16 (15) |
Calyx lobes irregular, to 4–6 mm. |
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(17) |
| + |
Calyx often undeveloped, rimlike or undulate, lobes 0.5–2 mm. |
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(18) |
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| 17 (16) |
Leaf blade base cuneate, rarely rounded, abaxial surface with scattered large scales; calyx with long
hairs; corolla white or pale reddish purple, inside with deep green spots. |
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60 Rhododendron searsiae |
| + |
Leaf blade base rounded, rarely broadly cuneate, abaxial surface scales all similar; calyx scaly along margin; corolla pale or deep purplish red, inside with or without brownish red spots. |
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61 Rhododendron concinnum |
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| 18 (16) |
Leaf blade base rounded or broadly cuneate. |
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(19) |
| + |
Leaf base narrower, cuneate to rounded. |
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(21) |
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| 19 (18) |
Petiole hispid; corolla purple or deep red, 3–4 cm. |
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62 Rhododendron amesiae |
| + |
Petiole glabrous; corolla pale yellow, pale red or rosy red, 1.2–3 cm. |
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(20) |
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| 20 (19) |
Leaf blade apex rounded, scales on abaxial surface flat, veins inconspicuous on both sides;
corolla not scaly outside. |
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63 Rhododendron oreotrephes |
| + |
Leaf blade apex obtuse to acute, apiculate; scales on abaxial surface concave, veins conspicuous
on both sides; corolla scaly outside. |
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64 Rhododendron tatsienense |
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| 21 (18) |
Leaf blade elliptic, 2.5–5 × 0.8–1.8 cm; corolla 1.5–1.8 cm. |
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65 Rhododendron xichangense |
| + |
Leaf blade elliptic, elliptic-lanceolate or oblong-lanceolate, 3–11 × 1.2–3.5 cm; corolla 1.6–3.5 cm. |
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(22) |
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| 22 (21) |
Leaf blade oblong or oblong-lanceolate; abaxial leaf surface with scales thin, gray-brown, contiguous or overlapping, to 0.5 × their own diameter apart. |
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66 Rhododendron polylepis |
| + |
Leaf blade elliptic or elliptic-lanceolate; abaxial leaf surface with scales rusty brown, 0.5–1(–2) × their own diameter apart. |
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67 Rhododendron siderophyllum |
