Common Name:

General Information

Rhododendron kesangiae is an evergreen shrub or a small tree that can grow around 15 metres tall.
The plant is harvested from the wild for local use as a fuel and food wrapper. The plant is often grown as an ornamental in gardens.
Rhododendron kesangiae is a common widely distributed species occurring through most of central Bhutan from west to east. It has a large extent of occurrence and is known from more than 16 localities. There are some minor localized threats but none are thought to be significant enough to be causing a continuing decline. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2015)[].

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

Range

E. Asia - Bhutan, northern India (Arunachal Pradesh)

Habitat

Found among Rhododendrons and bamboos in Fir (Abies densa) and Hemlock (Tsuga dumosa) forests, occurring on forested ridges in the zone immediately below and up to the tree line; at elevations from 2,890 - 3,450 metres[].

Properties

Conservation Status	Least Concern
Other Uses Rating
Habit	Evergreen Tree
Height	0.00 m
Pollinators	Bees, Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Rhododendron kesangiae is native to higher elevations of the temperate zone of,northern India and Bhutan where it can be found at elevations up to 4,000 metres. A moderately cold-tolerant plant, when fully dormant it can withstand temperatures down to about -18°c Although somewhat 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[].
Rhododendron species generally succeed when grown in a non-compacted, humus rich lime free soil and a position with some shade, preferably light woodland shade. They strongly dislike soils of a dry arid nature, heavy soils or clays[]. 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[].
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[].

Edible Uses

None known

Medicinal

None known

Other Uses

The large leaves are widely used in Bhutan to wrap food[]. The broadly elliptic to almost obovate leaves are 20 - 30cm long and 10 - 16cm wide.

The wood is used for fuel[].

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[].