Rhododendron arboreum
Family: Ericaceae
What it is like
Rhododendron arboreum is an evergreen Shrub growing to 12 m (39ft) by 3 m (9ft). See above for USDA hardiness. It is hardy to UK zone 7. It is in leaf all year, in flower from April to May. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: mildly acid soils and can grow in very acid soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.
Height (m): 12
Where it is found
Forests and shrubberies with Pieris ovalifolia and Quercus incana, 1500 - 3600 metres from Pakistan to S.E. Tibet in the Himalayas.
E. Asia - Himalayas to Sri Lanka.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 1
The tender leaves are used as a cooked vegetable. Caution is advised, see the notes above on toxicity. Flowers - raw or cooked. A sweet-sour taste, they are said to make a good sub-acid jelly. Th flowers are sometimes simply pickled by adding salt and chili. Caution is advised, large quantities can cause intoxication.
Medicine
Rating: 2
The young leaves are astringent and poultice. They are made into a pasteand then applied to the forehead in the treatment of headaches. The juice of the bark is used in the treatment of coughs, diarrhoea and dysentery. A decoction of the flowers is used to check a tendency to vomit, especially if there is also a loss of appetite. The juice of the flowers is used in the treatment of menstrual disorders. The petals are eaten to assist the removal of any animal bones that have become stuck in the throat.
Astringent: Produces contraction in living tissue, reducing the flow of secretions and discharges of blood, mucus, diarrhoea etc.
Dysentery: Used in treating dysentery - an infection of the intestines that causes diarrhoea containing blood or mucus.
Poultice: A moist, usually warm or hot, mass of plant material applied to the skin in the treatment of burns etc.
Stomachic: Aids and improves the action of the stomach.
Other
Rating:
The juice of the leaves is spread over cots and beds to get rid of bed lice. Wood - soft, even grained, seasons badly. Used in turnery, it can also be used to make charcoal and for fuel. Th wood is much employed in Nepal where it is used for making household implements, building small houses and fences. Planks of the wood are carved to make boxes, cupboards and other furniture. It is a very good fuel, burning well with a long-lasting heat - overcollection of the wod for fuel, and also for making charcoal, has become a cause for conservation concern.
Charcoal: Used for fuel, drawing, deodorant, filter, fertilizer etc.
Fuel: Usually wood, plant materials that have been mentioned as being a good fuel.
Repellent: Plants that are said to deter but not necessarily kill various mammals, birds, insects etc.
Wood: A list of the trees and shrubs that are noted for having useful wood.
How it is grown
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.
Propagating it: Seed - best sown in a greenhouse as soon as it is ripe in the autumn and given artificial light. Alternatively sow the seed in a lightly shaded part of the warm greenhouse in late winter or in a cold greenhouse in April. Surface-sow the seed and do not allow the compost to become dry. Pot up the seedlings when they are large enough to handle and grow on in a greenhouse for at least the first winter. Layering in late July. Takes 15 - 24 months. Cuttings of half-ripe wood, August in a frame. Difficult.
Best place to grow: Woodland Garden Secondary; Dappled Shade;
Habit: Shrub
Hardiness: 6-9
Growth:
Soil: Light (sandy), medium
Shade: Semi-shade, no shade
Moisture: Moist
Things to keep in mind
The leaves are poisonous. The flowers can cause intoxication in large quantities.