Rhododendron hypenanthum I.B.Balfour, treated here as a subspecies of Rhododendron anthopogon (as Rhododendron anthopogon subsp hypenanthum (I.B.Balfour) Cullen) is treated as a distincr species in the flora of China[].

Common Name:

General Information

Rhododendron anthopogon is an evergreen shrub of compact habit; it usually grows up to 60cm tall.
The plant is harvested from the wild in large quantities, mainly for medicinal use, but also use as a food and source of materials. The leaves and twigs are sold in local markets for use as an incense, whilst the leaves and the flowers are sold for medicinal use[, ]. The plant is grown as an ornamental.

Known Hazards

Although no specific mention of toxicity has been seen for this species, all parts of Rhododendron species (including the leaves, flowers and pollen) contain greater or lesser amounts of the toxic compound andromedotoxin (also known as grayanotoxin). Rarely lethal to humans (and used medicinally in some herbal disciplines), this compound 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 - W. China to the Himalayas.

Habitat

Moist open slopes, hillsides, ledges of cliffs and in thickets, often covering large areas; at elevations from 3,000 - 4,500, occasionally to 5,000 metres[, ].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Shrub
Height	0.60 m
Pollinators	Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Rhododendron anthopogon is a plant of high elevations in the Himalayas, generally growing well in the temperate zone in areas where winter temperatures do not usually fall below around -15°c[]. Although cold-tolerant when dormant, the flowers and young growth of Rhododendrons are very susceptible to damage by late frosts in regions where these are likely to occur after new growth has commenced in the spring[].
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[].
Rhododendron species are mainly woodland species that grow well in the dappled shade and shelter given by the other woodland plants. They are surface-rooting species with a fibrous root system, however, and do not grow well close to trees that are also surface-rooting, nor do they do well with ground cover or other small plants growing over or into their roots[, ].
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[].
The whole plant is strongly aromatic with a slightly acrid odour, especially when crushed[].
Plants in this genus are notably susceptible to honey fungus[].

Edible Uses

The flowers are used as a tea substitute[]. Some caution is advised - see the notes above on toxicity.

Medicinal

Rhododendron anthopogon is a commonly used medicinal plant in India, where it is gathered from the wild in large quantities[]. Some caution is advised in the medicinal usage of this plant - see the notes above on toxicity.

The stems and leaves of the sub-species Rhododendron anthopogon hypenanthum are used in Tibetan herbalism[, ]. They have a sweet, bitter and astringent taste and they promote heat[]. They are antitussive, diaphoretic and digestive and are used to treat lack of appetite, coughing and various skin disorders[]. The powdered, dried leaves and young shoots are eaten with butter in the treatment of leucorrhoea and gonorrhoea[].

The flowers of the sub-species Rhododendron anthopogon hypenanthum are also used in Tibetan medicine, having a sweet taste and neutral potency[]. They are antitussive, febrifuge and tonic, being used in the treatment of inflammations, lung disorders and general weakening of the body[]. They are also used when water and locality are not agreeable due to a change of environment[].

The leaves are stimulant[]. A decoction of the leaves is used in the treatment of colds, coughs, chronic bronchitis, asthma and excessive mucus formation in the nose or throat[]. In Nepal, the leaves are boiled and the vapour inhaled to treat coughs and colds[].
The aromatic leaves are used as a snuff to produce sneezing[].

The leaves and flowers are used in treating indigestion and lung infection in Pso-ring-pa (an indigenous system of medicine among Tibetans)[].
The dried and powdered flowers, mixed with oil, are used as massage oil for the body in the treatment of post-delivery complications[].

Other Uses

The leaves contain around 0.2% essential oil[]. The dried leaves are used as incense[]. The leaves and twigs, often mixed with those of Juniperus species, are burnt as incense in temples and monasteries[]

The dried, powdered leaves and flowers are used as ingredients in commercial cosmetic preparations as a humectant[].
An extract of the flowers and leaves is used as an ingredient in commercial cosmetic preparations as a skin conditioner[].

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[].