Rhododendron arboreum
| Rhododendron arboreum | |
|---|---|
 | |
| R. arboreum subsp. arboreum in central Nepal | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Ericales |
| Family: | Ericaceae |
| Genus: | Rhododendron |
| Species: | R. arboreum |
| Binomial name | |
| Rhododendron arboreum | |
Rhododendron arboreum, the tree rhododendron,[2] is an evergreen shrub or small tree with a showy display of bright red flowers. It is found in Bhutan, China, India, Myanmar, Nepal, Sri Lanka, Pakistan and Thailand.[3] It is the national flower of Nepal.
Description
[edit]Its specific epithet means "tending to be woody or growing in a tree-like form".[citation needed] It has been recorded as reaching heights of 20 m (66 ft),[4] though it is more usually 12 m (39 ft) tall and broad. This plant holds the Guinness Record for the World's Largest Rhododendron. The tree discovered in 1993 at Mount Japfü in the Kohima District of Nagaland, India, holds the Guinness Record for the tallest Rhododendron at 20 m (65 ft).[5] In sharp contrast to this, the New Guinean epiphytic species Rhododendron caespitosum never exceeds 10 cm (4 in) in height.[6]
In early and mid spring, trusses of 15–20 bell-shaped flowers, 5 cm (2 in) wide and 3–5 cm (1–2 in) long are produced; they are red, pink or white, with black nectar pouches and black spots inside.
Taxonomy
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Subspecies
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The Plants of the World Online database accepts five subspecies:[7]
- Rhododendron arboreum subsp. albotomentosum (Davidian) D.F.Chamb. has leaves with whitish hairs beneath; it occurs in Myanmar.
- Rhododendron arboreum subsp. arboreum, occurring in the Himalaya.
- Rhododendron arboreum subsp. cinnamomeum (Wall. ex G.Don) Tagg has leaves with cinnamon-brown hairs beneath; it occurs in the central & eastern Himalaya to southern Tibet.
- Rhododendron arboreum subsp. nilagiricum (Zenker) Tagg is found in the Nilgiri Mountains in Tamil Nadu, India.[8]
- Rhododendron arboreum subsp. zeylanicum (T.J.Booth) Tagg; a rare subspecies endemic in the highlands of Sri Lanka, named after Zeilan, the name used by Arabian traders to refer to Sri Lanka
Habitat
[edit]Rhododendron arboreum is found in the Pakistan, India, Nepal, Myanmar, Sri Lanka, the Himalayas, Northeast India, and Tibet. It is introduced in Madeira.[7]
It is the national flower of Nepal.[9] In India it is the state tree of Uttarakhand and state flower of Nagaland. It is the provincial flower of Sri Lanka's Central Province.
Cultivation
[edit]Rhododendron arboreum prefers moist but well-drained, leafy, humus-rich, acid pH soil, in dappled shade. It has broad, dark green leaves, 7–19 cm (3–7.5 in) long, with a silvery, fawn or brown hairy coating beneath.
This plant is suitable for woodland gardens.
Shelter is imperative to prevent wind damage to leaves.
Threats
[edit]Rhododendrons are susceptible to vine weevil, rhododendron and azalea whiteflies, leafhoppers, lacebugs, scale insects, caterpillars, aphids, powdery mildew, bud blast, honey fungus, rust, leafy gall, petal blight, silver leaf, phytophthora root rot and lime-induced chlorosis.[11]
See also
[edit]- Catawbiense hybrid – hybrid with R. arboreum
References
[edit]- ↑ Botanic Gardens Conservation International (BGCI) & IUCN SSC Global Tree Specialist Group (2018). "Rhododendron arboreum". IUCN Red List of Threatened Species. 2018 e.T136143885A136143887. doi:10.2305/IUCN.UK.2018-2.RLTS.T136143885A136143887.en. Retrieved 27 June 2026.
- ↑ BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 26 June 2015. Retrieved 17 October 2014.
- ↑ "Rhododendron arboreum". American Rhododendron Society. Archived from the original on 14 May 2025. Retrieved 20 December 2025.
- ↑ "Tree rhododendrons". Richard Francis. Archived from the original on 19 July 2008. Retrieved 29 July 2008.
- ↑ "Largest Rhododendron". Guinness Book of World Records.
- ↑ Sleumer, H. Flora Malesiana – Ericaceae. Vol. 4 (series 1). p. 571.
- 1 2 "Rhododendron arboreum Sm". Plants of the World Online. Retrieved 30 September 2025.
- ↑ Chamberlain, D. F. 1982. A revision of Rhododendron II. Subgenus Hymenanthes. Notes Roy. Bot. Gard. Edinburgh 39:331.
- ↑ Rohit Kumar (1999). Nepal, Nature's Paradise: Insight Into Diverse Facets of Topography, Flora & Ecology. p. 188. ISBN 978-9748614946.
- ↑ P. F. Fyson (1915), The flora of the Niligiri and Pulney Hill-Tops (Above 6,500 Feet), Being the Wild and Commoner Introduced Flowering Plants Round the Hill-Stations of Kodaikanal, Ootacamund, Kotagiri and Kodaikanal, with 286 full page illustrations and 4 maps, vol. II, Madras: Superintendent, Government Press, p. 179
- ↑ The Royal Horticultural Society (2008) RHS Garden Hyde Hall Plant of the month: April, retrieved 19 February 2008 Gardens Archived 20 November 2005 at the Wayback Machine
