Common Name: Chinese Azalea

General Information

Rhododendron molle is a deciduous shrub that can grow from 50 - 200cm tall.
The plant is harvested from the wild for local use as a medicine and source of materials. It is widely grown as an ornamental and is a parent of many cultivars.

Known Hazards

The plant is very toxic[].
Although no other 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 - southeastern China - Sichuan to Jinagsu, south to Yunnan and Guangdong.

Habitat

Thin pine forests, thickets on mountain slopes, exposed grassy hill-sides, ridges; at elevations from near sea level to 2,500 metres[, ].

Properties

Medicinal Rating
Other Uses Rating
Habit	Deciduous Shrub
Height	1.50 m
Pollinators	Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Rhododendron molle is a moderately cold-hardy plant, able to tolerate temperatures down to around -10 to -15°c when fully dormant[]. 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, though it prefers a shady position[]. 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[].
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[].
A very ornamental plant[], it is the parent of many cultivars[].
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 analgesic, anaesthetic and sedative[]. They are applied externally in the treatment of arthritis, caries, itch, maggots and traumatic injuries[].
The root is used in the treatment of arthritis, rheumatism and traumatic injuries[].

Other Uses

The powdered flowers have a mild insecticidal effect[].

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[].