Rhododendron subsect. Fortunea in Flora of China @ efloras.org

1. Rhododendron subsect. Fortunea (Tagg) Sleumer, Bot. Jahrb. Syst. 74: 546. 1949.

云锦杜鹃亚组 yun jin du juan ya zu

Fang Mingyuan (方明渊); David F. Chamberlain

Rhododendron ser. Fortunea Tagg in J. B. Stevenson, Sp. Rhodod. 257. 1930 ["Fortunei"].

Shrubs or trees; bark rough; young shoots with white to grayish tomentose indumentum, soon glabrescent. Leaf blade oblong-elliptic, elliptic, oblanceolate, ovate to suborbicular; abaxial surface floccose or not on midrib, rarely with a sparse white stellate indumentum (R. asterochnoum); adaxial surface glabrous when mature. Inflorescence lax, 5–30-flowered, rachis 3–70 mm; calyx minute to well-developed, 1–20 mm; corolla funnel-campanulate to open-campanulate, 5–7(–8)-lobed, white or pale pink to purple, nectar pouches usually absent (apparently present in R. praeteritum); stamens 10–16(–22); ovary glandular or glabrous; style glabrous or glandular-hairy to tip.

Thirty-one species: Bhutan, China, India, Myanmar, Nepal, Sikkim, Vietnam; 31 species (28 endemic) in China.

Rhododendron magorianum Millais (Rhododendrons, ser. 2, 182. 1924) was described from cultivated material derived from seed (E. H. Wilson 1539) collected in W China. Unknown in the wild, it is presumed to be a hybrid of a species in R. subsect. Fortunea.

Rhododendron planetum I. B. Balfour (Notes Roy. Bot. Gard. Edinburgh 12: 145. 1920) is probably a hybrid of a species in R. subsect. Fortunea. It was described from a plant raised from seed that was supposed to have been collected in Sichuan, but the collector’s number cited is wrong. The provenance of this seed is therefore uncertain.

1 Calyx 7–20 mm. 203 Rhododendron griffithianum

+ Calyx 1–7(–10) mm. (2)

2 (1) Outer surface of corolla with dense long-stipitate glands. (3)

+ Outer surface of corolla eglandular, or with sparse short stipitate glands. (6)

3 (2) Abaxial leaf surface sparsely floccose; blade oblong-obovate, 18.5–22.5 × 8–9.5 cm; petiole 3.5–4.2 cm; young shoots eglandular; corolla funnel-campanulate, ca. 6.5 cm, lobes 7. 205 Rhododendron xiaoxidongense

+ Abaxial leaf surface glabrous. (4)

4 (3) Young shoots glabrous. 233 Rhododendron serotinum

+ Young shoots glandular hairy. (5)

5 (4) Leaf blade 22–25 × 7.5–8.8 cm; petiole 4–4.5 cm; corolla 9.5–10 cm, lobes 5. 204 Rhododendron magniflorum

+ Leaf blade 10–19 × 3.2–4.5 cm; petiole 1.6–3 cm; corolla 5–6 cm; lobes 7 or 8. 206 Rhododendron glanduliferum

6 (2) Stigma 5–6.5 mm in diam., swollen, discoid. (7)

+ Stigma to 5 mm in diam., capitate or discoid. (13)

7 (6) Corolla broadly campanulate or campanulate. (8)

+ Corolla obliquely campanulate, funnel-campanulate or widely funnel-campanulate. (9)

8 (7) Corolla broadly campanulate, lobes 5–7; stamens 15–22; leaves oblong-oblanceolate to oblong- lanceolate, abaxial surface glabrous or sparsely tomentose along midrib. 207 Rhododendron calophytum

+ Corolla campanulate, lobes 5; stamens 18–20; leaves oblanceolate, rarely oblong-elliptic, abaxial surface with stellate hairs when mature. 208 Rhododendron asterochnoum

9 (7) Corolla obliquely or ventricose-campanulate, purple, lobes 5; leaf blade abaxially densely white-floccose, later glabrescent. 209 Rhododendron jingangshanicum

+ Corolla funnel-campanulate to tubular-campanulate, white to pale pink (not recorded for R. miyiense and R. wolongense), lobes 6–8; leaf blade abaxially glabrous. (10)

10 (9) Inflorescence 5–6-flowered; pedicel 1.8–2 cm. (11)

+ Inflorescence 8–12-flowered; pedicel 2.5–4 cm. (12)

11 (10) Leaf blade 3–4.5 cm wide; pedicel glandular; corolla ca. 5 cm, outer surface glandular. 211 Rhododendron wolongense

+ Leaf blade 5.3–6.2 cm wide; pedicel glabrous; corolla 9.5–10.5 cm, outer surface glabrous. 213 Rhododendron miyiense

12 (10) Filaments glabrous, 3.7–4.9 cm; leaf apex acute, apiculate; inflorescence rachis ca. 5 cm. 210 Rhododendron faithiae

+ Filaments puberulent at base, 2–3 cm; leaf apex obtuse, apiculate; inflorescence rachis 2–2.5 cm. 212 Rhododendron decorum

13 (6) Ovary and style glabrous. (14)

+ Ovary densely glandular; style glabrous or glandular. (18)

14 (13) Leaf blade (8–)10–22 cm, lobes 5; stamens (12–)15–16. (15)

+ Leaf blade 4.5–10 cm; lobes 5 or 7–8; stamens 10–14. (17)

15 (14) Leaf blade oblong-oblanceolate, abaxial surface with midrib grayish tomentose; corolla funnel-campanulate; pedicel white-puberulent. 214 Rhododendron sutchuenense

+ Leaf blade elliptic-oblanceolate, abaxial surface entirely glabrous; corolla campanulate, white tinged with rose; pedicel 1.5–3 cm, glabrous. (16)

16 (15) Corolla 5.8–6.2 cm. 215 Rhododendron praevernum

+ Corolla 3–4.5 cm. 216 Rhododendron guihainianum

17 (14) Leaf blade midrib glabrous abaxially; pedicel 0.5–1.5 cm; corolla with nectar pouches absent, lobes 5–8; stamens 12–14. 217 Rhododendron oreodoxa

+ Leaf blade midrib with sparse loose hairs abaxially; pedicel 1.8–2 cm; corolla with 5 basal nectar pouches, lobes 5; stamens 10. 218 Rhododendron praeteritum

18 (13) Ovary densely red- or rufous-glandular. (19)

+ Ovary densely white-glandular. (20)

19 (18) Filaments glabrous; leaf blade base rounded; inflorescence 3–5-flowered, rachis 2–2.5 cm. 219 Rhododendron vernicosum

+ Filaments pubescent at base; leaf blade base auriculate-cordate; inflorescence 6–10-flowered, rachis ca. 1 cm. 220 Rhododendron nymphaeoides

20 (18) Leaf blade base auriculate-cordate, rarely subcordate or rounded (R. orbiculare subsp. cardiobasis), 4–10.5 cm wide; petiole 2–7.5 cm. (21)

+ Leaf blade base cuneate to rounded, rarely cordate and then blade less than 4.6 cm wide; petiole 1–2.5(–4) cm. (23)

21 (20) Corolla rose, 3.2–3.5 cm; inflorescence rachis 1.5–2.5 cm 224 Rhododendron orbiculare

+ Corolla white, ca. 6–6.5 cm; inflorescence rachis 3–7 cm. (22)

22 (21) Petiole 5–7.5 cm; inflorescence rachis 5.5–7 cm. 221 Rhododendron hemsleyanum

+ Petiole 2–3.5 cm; inflorescence rachis 2–3.5 cm. 233 Rhododendron serotinum

23 (20) Filaments puberulent near base. (24)

+ Filaments glabrous. (25)

24 (23) Petiole winged, up to 10 mm wide; style ca. 3.7 cm; pedicel not warty but glandular; calyx glabrous. 226 Rhododendron platypodum

+ Petiole terete; style 1.6–1.8 cm; pedicel warty and glandular; calyx glandular. 227 Rhododendron verruciferum

25 (23) Calyx 2–5(–10) mm; pedicel glabrous or sparsely glandular. (26)

+ Calyx to 2 mm, sometimes discoid; pedicel stipitate-glandular. (27)

26 (25) Inflorescence 6–8(–10)-flowered; pedicel 2–2.5 cm; leaf apex obtuse; corolla pale pink to white. 229 Rhododendron discolor

+ Inflorescence 10–13-flowered; pedicel 3.5–4.2 cm; leaf apex acute or cuspidate; corolla red to purple or lilac (see also 232. R. liboense). 231 Rhododendron huanum

27 (25) Corolla white, 6–6.5 cm; leaf blade with 19–21 lateral veins each side of midrib. 225 Rhododendron maoerense

+ Corolla white flushed pink with yellow flecks or pink to rose-purple, 3.5–6 cm; leaf blade with 14–18 lateral veins each side of midrib. (28)

28 (27) Leaf blade 4.5–6.6 cm; inflorescence ca. 15-flowered; corolla white flushed pink, with yellow flecks, 3.2–3.5 cm. 228 Rhododendron gonggashanense

+ Leaf blade 8–16 cm; inflorescence 6–12-flowered; corolla pink to rose-purple, sometimes with dark purple flecks, 3.5–6 cm. (29)

29 (28) Leaf blade base rounded or truncate, rarely cordulate; apex obtuse to rounded, rarely acute; style ca. 3 cm. 222 Rhododendron fortunei

+ Leaf blade base cuneate; apex acute to acuminate; style 4–4.5 cm. (30)

30 (29) Inflorescence rachis 3–6 cm, glandular and tomentose; pedicel ca. 1 cm. 230 Rhododendron davidii

+ Inflorescence rachis 2–2.5 cm, glabrous; pedicel 2.7–3.4 cm; corolla 3.5–4.5 cm. 223 Rhododendron jinchangense

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