All Floras      Advanced Search
FOC Vol. 14 Page 261 Login | eFloras Home | Help
FOC | Family List | FOC Vol. 14 | Ericaceae

1. Rhododendron sect. Rhododendron

杜鹃组 du juan zu

Shrubs, sometimes prostrate or cushion-forming, or small trees, usually evergreen, seldom deciduous, sometimes epiphytic. Leaves small to large; leaf blade margin usually entire, sometimes crenulate or revolute; abaxial surface scaly, sometimes also uniformly woolly, or pubescent or strap-shaped-setose along main veins. Inflorescence terminal, 1–28-flowered, or 2- or 3-flowered and axillary, usually umbellate-racemose, shortly racemose or capitate; flowers small to large. Calyx generally short, lobes leaflike or absent, rarely well-developed; corolla funnelform, to campanulate or tubular-campanulate. Stamens (4–)5–10(–25); filaments mostly pubescent towards base, rarely glabrous; ovary 5(–12)-locular, always scaly, sometimes also hairy; style long, slender, straight, curved, or sharply deflexed, glabrous or with scales or shortly pilose at base. Capsule ovoid to cylindric, valves woody, 2–23(–70) mm, scaly or not, sometimes pubescent. Seeds wingless or with a finlike wing.

About 170 species: mostly in Asia, especially from the E Himalayas to SW China, a few species in Europe and North America; 153 species (92 endemic) in China.

1 Style short, thick, distinctly curved.   (2)
+ Style slender and straight.   (8)
2 (1) Stamens 12–16; corolla with wool-like hairs in the throat.   15 Rhododendron subsect. Camelliiflora
+ Stamens (8–)10; corolla glabrous inside.   (3)
3 (2) Scales strongly dimorphic, the larger dark brown, the smaller golden.   16 Rhododendron subsect. Glauca
+ Scales on abaxial leaf surface monomorphic.   (4)
4 (3) Pedicels shorter than corolla; corolla usually yellow, rarely white or pink.   14 Rhododendron subsect. Boothia
+ Pedicels distinctly longer than corolla.   (5)
5 (4) Inflorescences corymbose, 1–3(–5)-flowered; leaves 0.4–2.6(–4) cm.   (6)
+ Inflorescences racemose, 4–10(–18)-flowered; leaves (2–)4–5 cm.   (7)
6 (5) Corolla fleshy, crimson or purple, with scales outside; abaxial leaf surface with distant scales.   17 Rhododendron subsect. Campylogyna
+ Corolla thinner, variable in color, with dense scales outside; abaxial leaf surface with dense scales.   19 Rhododendron subsect. Lepidota
7 (5) Scales entire, small, distant on abaxial surface of leaves; corolla campanulate.   18 Rhododendron subsect. Genestieriana
+ Scales crenulate, overlapping on abaxial surface of leaves; corolla rotate.   20 Rhododendron subsect. Baileya
8 (1) Leaf blade abaxially woolly, hairs obscuring small golden scales.   1 Rhododendron subsect. Edgeworthia
+ Leaf blade abaxially without hairs, or rarely with hairs that do not obscure the scales.   (9)
9 (8) Style with scales, at least at base, sometimes up to tip, rarely without scales; calyx usually conspicuously lobed, occasionally with underdeveloped lobes, then with margin ciliate.   (10)
+ Style entirely without scales; calyx lobes inconspicuous, rarely more than 4 mm.   (11)
10 (9) Corolla (3–)5–7(–13.5) cm, often white or pink, rarely yellow.   2 Rhododendron subsect. Maddenia
+ Corolla 1.5–3 cm, yellow, white, pink or dark purple.   12 Rhododendron subsect. Tephropepla
11 (9) Inflorescences racemose; corolla tubular or campanulate.   (12)
+ Inflorescences corymbose; corolla funnelform or broadly campanulate, rarely tubular-campanulate.   (13)
12 (11) Corolla usually pendulous, 2–3.8 cm, often brightly colored, never white, outer surface not lepidote.   11 Rhododendron subsect. Cinnabarina
+ Corolla not pendent, 0.4–1.2 cm, white or yellow, outer surface lepidote.   13 Rhododendron subsect. Micrantha
13 (11) Corolla thin or fleshy, tubular or narrowly campanulate, lobes short, straight or spreading, though not markedly so.   (14)
+ Corolla thin, funnelform or rotate, lobes spreading.   (15)
14 (13) Inflorescences 1–3-flowered; flowers erect; corolla thin, often yellow, outer surface scaly.   4 Rhododendron subsect. Monantha
+ Inflorescences 2–6(–8)-flowered; flowers usually pendulous; corolla fleshy, various in color, sometimes yellow, outer surface not scaly.   11 Rhododendron subsect. Cinnabarina
15 (13) Low to tall shrubs, rarely small trees, leaves large, (0.9–)1.3–12 × (0.3–)0.8–3.5(–4) cm.   (16)
+ Low to dwarf shrubs; leaves small to very small, 0.3–4(–7) × 0.15–1.7(–2.8) cm.   (18)
16 (15) Inflorescences mostly 5–7(–10)-flowered; corolla always scaly outside.   6 Rhododendron subsect. Heliolepida
+ Inflorescences mostly 1–3-flowered, sometimes with 2 or 3 lateral buds below terminal buds; corolla with or without scales outside.   (17)
17 (16) Small shrubs, usually epiphytic; calyx well-developed, lobes red or rosy-purple, rarely green; young shoots usually setose; corolla open-campanulate.   3 Rhododendron subsect. Moupinensia
+ Medium to tall shrubs, rarely small trees, terrestrial; calyx rim-like or shortly lobed; young shoots usually glabrous; corolla broadly funnelform.   5 Rhododendron subsect. Triflora
18 (15) Pedicels 1–5(–15)mm; corolla usually glabrous outside (puberulous in R. dasypetalum).   (19)
+ Pedicels (7–)15–30 mm; corolla pubescent outside.   (20)
19 (18) Leaf margin entire; scales on abaxial surface flat, with relatively broad rims.   7 Rhododendron subsect. Lapponica
+ Leaf margin crenulate; scales on abaxial surface vesicular.   9 Rhododendron subsect. Fragariiflora
20 (18) Abaxial leaf surface with scales dense and overlapping, margin crenulate.   8 Rhododendron subsect. Saluenensia
+ Abaxial leaf surface with scales sparser, 0.5–6 times their own diameter apart, margin entire.   10 Rhododendron subsect. Uniflora

  • List of lower taxa


  • Flora of China @
    Browse by
    Advanced Search

    Flora of China Home




     |  eFlora Home |  People Search  |  Help  |  ActKey  |  Hu Cards  |  Glossary  |