Common Name: Rosebay

General Information

Rhododendron aureum is a dwarf, evergreen shrub with horizontal stems and obliquely ascending branchlets; it usually grows from 50 - 100cm tall[, ].
The plant is harvested from the wild for local use as a medicine. It is an ingredient of commercial cosmetic preparations and is sometimes grown as an ornamental.

Known Hazards

All parts of the plant (including the leaves, flowers and pollen) contain greater or lesser amounts of the toxic compound andromedotoxin (also known as grayanotoxin), as well as the glycosides ericolin and rhododendrin[, ].
Rarely lethal to humans (and used medicinally in some herbal disciplines), andromedotoxin causes dose-dependant overstimulation of the central nervous system with symptoms including various cardiovascular effects (mainly low blood pressure and cardiac rhythm disorders); nausea and vomiting; and a change in consciousness. The effects commence shortly after ingestion and last around two days. These effects are also transferred to honey made from the nectar of the flowers. In some parts of the world bees are used to deliberately produce a honey rich in andromedotoxin which is then eaten for its supposed medicinal, hallucinogenic and aphrodisiac effects.
In contrast to humans, many other creatures are more susceptible to the toxin and it has sometimes proved lethal to grazing animals and household pets. Some forms of honeybees are also killed by the toxin (resistant forms of the bee are used for honey production). Bumblebees are not affected, however, and are also more efficient in pollinating rhododendron flowers, so one theory is that the toxin is produced by the plant in order to favour the bumblebee and improve fertilization rates[].

Botanical References

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Range

E. Asia - southern Siberia, Russian Far east, northeast China, northern and central Japan, Korea.

Habitat

Forming thickets in high mountain areas, both alpine and sub-alpine[]. Grasslands and amongst bryophytes, in the alpine region; at elevations from 1,000 - 2,500 metres[].

Properties

Medicinal Rating
Habit	Evergreen Shrub
Height	0.50 m
Growth Rate	Slow
Pollinators	Insects
Cultivation Status	Wild

Cultivation Details

Rhododendron aureum is a very cold-tolerant plant, when fully dormant it can withstand temperatures down to about -40°c. The plant usually comes into growth with the first mild weather in late winter or early spring - although it is very cold-tolerant when dormant, the flowers and young growth are very susceptible to damage by late frosts in regions where these are likely to occur after the new growth has commenced[].
Succeeds in a most humus-rich lime-free soils except those of a dry arid nature or those that are 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[]. A pH between 4.5 and 5.5 is ideal[].
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[].
A slow-growing species[].
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[].
Closely related to Rhododendron caucasicum[].
This species is very rare and difficult to cultivate[, ].
Plants in this genus are notably susceptible to honey fungus[].

Edible Uses

None known

Medicinal

Some caution is advised in the medicinal usage of this plant - see the notes above on toxicity.

The flowers are used in Tibetan medicine, they are said to have a bitter taste and a neutral potency[]. Haemostatic, they are used in the treatment of spreading pus and blood in the thoracic region, especially the lungs[].
Caution should be exercised when using the flowers because they are toxic[].

A decoction of the leaves is diaphoretic and is used in the treatment of rheumatism and gout[].

Other Uses

An extract of the leaves is used as an ingredient in commercial cosmetic preparations as a masking agent, soothing agent, skin protector[].

Propagation

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 mid spring. 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[].