Rhododendron arboreum

Rhododendron arboreum, the tree rhododendron, 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. It is the national flower of Nepal.

Description

A small evergreen tree. It can be 1-8-15 m high. It can spread 4.5 m high. The leaves have stalks. The leaves are crowded towards the ends of the branches. Leaves are 4.5-16 cm long by 1.5-6 cm wide. They are oblong to sword shaped and narrow at both ends. They are silvery underneath. The flowers are red, white or pink. The flowers are crowded in large round heads. There are 10 stamens. The fruit capsule is 1.5-2 cm long. It has ribs along it.

Edible Uses

The tender leaves can be used as a cooked vegetable, though caution is advised regarding toxicity. The flowers can be eaten raw or cooked — they have a sweet-sour taste and are said to make a good sub-acid jelly. They are sometimes simply pickled with salt and chili. Caution is advised, as large quantities of the flowers can cause intoxication.

Traditional Uses

The flower petals are eaten raw. They are also used to make jelly. The juice from them is used to make drinks. They are also used for colouring drinks and syrups. They are also used for chutney. The flower can be pickled with salt and chili. CAUTION: The young leaves are poisonous. The young leaves are cooked as a vegetable. They are boiled.

Medicinal Uses

The young leaves are astringent and used as a poultice — made into a paste and applied to the forehead to treat headaches. Juice from the bark is used to treat coughs, diarrhoea and dysentery. A decoction of the flowers is used to suppress vomiting, particularly when accompanied by loss of appetite, and flower juice is used in the treatment of menstrual disorders. The petals are eaten to help dislodge animal bones stuck in the throat.

Known Hazards

Caution is advised regarding toxicity of the leaves. Large quantities of the flowers can cause intoxication.

Distribution

A tropical and subtropical plant. It grows in the highlands of Vietnam between 2,550 and 3,000 m altitude. In Nepal it grows between 1400-3300 m altitude. It grows on hillsides in mixed oak forests. It is native to the Himalayas. It suits hardiness zones 7-9. Arboretum Tasmania.

Where It Grows

Asia, Australia, Bhutan, China, Himalayas, India, Indochina, Myanmar, Nepal, Northeastern India, NW India, Pakistan, SE Asia, Sikkim, Sri Lanka, Tasmania, Thailand, Tibet, Vietnam,

Cultivation

Succeeds in most humus rich lime free soils except those of a dry arid nature or heavy or clayey. Prefers a peaty or well-drained sandy loam. Succeeds in sun or shade, the warmer the climate the more shade a plant requires. Requires a pH between 4.5 and 5.5. Hardy to between -10 and -15°c, the pink flowered form is hardier than the red. Succeeds in a woodland though, because of its surface-rooting habit, it does not compete well with surface-rooting trees. Plants need to be kept well weeded, they dislike other plants growing over or into their root system, in particular they grow badly with ground cover plants, herbaceous plants and heathers. There are many named varieties selected for their ornamental value. Plants form a root ball and are very tolerant of being transplanted, even when quite large, so long as the root ball is kept intact. This plant is the national flower of Nepal. The flowers are sold in local markets and used as offerings to the Gods and Godesses. A very ornamental plant, it is not very hardy outdoors in much of Britain, but grows well in the milder areas of the country. Plants in this genus are notably susceptible to honey fungus.

Propagation

Sow seed in a greenhouse as soon as it is ripe in autumn, providing artificial light. Alternatively, sow in a lightly shaded part of a warm greenhouse in late winter, or in a cold greenhouse in April. Surface-sow and keep the compost consistently moist. Pot up seedlings once large enough to handle and grow on under glass for at least the first winter. Layering in late July takes 15–24 months. Cuttings of half-ripe wood taken in August and rooted in a frame are difficult.

Other Uses

Leaf juice spread over cots and beds repels bed lice. The wood is soft and even-grained but seasons poorly; it is used in turnery, for making charcoal and as fuel. In Nepal it is widely used for household implements, building small houses and fences, and planks are carved into boxes, cupboards and other furniture. It burns well with long-lasting heat, though overcollection for fuel and charcoal has become a conservation concern.

Production

It is slow growing.

Other Information

The flower petals are eaten raw especially by children.

Notes

There are over 500 Rhododendron species.

Synonyms

Also Known As

Ardawal, Aru, Baras, Bhorans, Braah, Brash, Broa, Brus, Burah, Burans, Buransh, Burars, Burash, Chacheon, Chahan, Chak-hlei, Chhan, Chhawk-hlei-par-sen, Chiu, Daipa, Dieng-tiew-saw, Dieng-tin-thuin, Dotial, Etok, Ghonas, Gunras, Gurans, Guras, Gurash, Gurauns, Hardulli, Kamri, Lal hardul, Lalgurus, Laligurans, Laliguras, Lidainipa, Mandal, Ngeisoh, Ngay-sheek, Pori, Samu, Surang, Taggu, Takro, Taung-zalat-ni, Tin-saw, Zalutri

References (44)

• Altschul, S.V.R., 1973, Drugs and Foods from Little-known Plants. Notes in Harvard University Herbaria. Harvard Univ. Press. Massachusetts. no. 3175
• Ambasta S.P. (Ed.), 2000, The Useful Plants of India. CSIR India. p 521
• Aryal, K. P., et al, 2018, Diversity and use of wild and non-cultivated edible plants in the Western Himalaya. Journal of Ethnobiology and Ethnomedicine (2018) 14:10
• Bahuguna, A. et al, 2010, Floristic Diversity and Indigenous uses of Forest Vegetation of Dabka Watershed in Indian Central Himalayas. Ethnobotanical Leaflets 14:491-510
• Brickell, C. (Ed.), 1999, The Royal Horticultural Society A-Z Encyclopedia of Garden Plants. Convent Garden Books. p 869

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