If you would like to support this site, please consider Donating.
Useful Temperate Plants

Rhododendron thomsonii

Hook.f.

Ericaceae

+ Synonyms

Rhododendron lopsangianum Cowan

Common Name:

No Image.

General Information

Rhododendron thomsonii is an evergreen shrub or small tree growing from 2 - 4 metres tall[
266
Title
Flora of China
Publication
 
Author
 
Website
http://flora.huh.harvard.edu/china/
Publisher
Missouri Botanical Garden Press; St. Louis.
Year
1994
ISBN
 
Description
An excellent, comprehensive resource in 25 volumes. In addition to the botanical information the flora also gives basic information on habitat and some uses. An on-line version is also available.
].
The plant is used locally to make an insecticide. It is often grown as an ornamental in gardens, valued especially for its beautiful dark crimson flowers[
146
Title
A Manual of Indian Timbers.
Publication
 
Author
Gamble. J. S.
Publisher
Bishen Singh Mahendra Pal Singh
Year
1972
ISBN
-
Description
First written in the 19th century, but still a classic, giving a lot of information on the uses and habitats of Indian trees. Not for the casual reader.
].

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[
1668
Title
Grayanotoxin Poisoning: ‘Mad Honey Disease’ and Beyond
Publication
Cardiovasc Toxicol (2012) 12:208-215
Author
Jansen S.A. et al
Website
https://doi.org/10.1007/s12012-012-9162-2
Publisher
 
Year
2012
ISBN
 
Description
An in-depth review of the literature on the toxic effects of a toxin widely found in the family Ericaceae
].

Botanical References

200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
,
266
Title
Flora of China
Publication
 
Author
 
Website
http://flora.huh.harvard.edu/china/
Publisher
Missouri Botanical Garden Press; St. Louis.
Year
1994
ISBN
 
Description
An excellent, comprehensive resource in 25 volumes. In addition to the botanical information the flora also gives basic information on habitat and some uses. An on-line version is also available.

Range

E. Asia - Himalayan regions of China (Xizang), northern India (Sikkim, Arunachal Pradesh), Nepal, Bhutan

Habitat

Mixed forests, thickets, rocky slopes; at elevations from 3,000 - 4,000 metres[
266
Title
Flora of China
Publication
 
Author
 
Website
http://flora.huh.harvard.edu/china/
Publisher
Missouri Botanical Garden Press; St. Louis.
Year
1994
ISBN
 
Description
An excellent, comprehensive resource in 25 volumes. In addition to the botanical information the flora also gives basic information on habitat and some uses. An on-line version is also available.
].

Properties

Other Uses Rating *  *
HabitEvergreen Shrub
Height3.00 m
PollinatorsBees, Insects
Cultivation StatusOrnamental, Wild

Cultivation Details

Rhododendron thomsonii is a moderately cold-hardy plant, able to tolerate temperatures down to around -20°c when fully dormant[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
]. Although cold-tolerant when dormant, the flowers and young growth of this species are very susceptible to damage by late frosts in regions where these are likely to occur after new growth has commenced in the spring[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
].
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[
1
Title
RHS Dictionary of Plants plus Supplement. 1956
Publication
 
Author
F. Chittendon.
Publisher
Oxford University Press
Year
1951
ISBN
-
Description
Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [200]).
]. Prefers a peaty or well-drained sandy loam[
1
Title
RHS Dictionary of Plants plus Supplement. 1956
Publication
 
Author
F. Chittendon.
Publisher
Oxford University Press
Year
1951
ISBN
-
Description
Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [200]).
]. Succeeds in sun or shade, the warmer the climate the more shade a plant requires[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
]. Requires a pH between 4.5 and 5.5[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
].
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[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
,
352
Title
KemperCentreForHomeGardeningPlantFinder
Publication
 
Author
 
Website
http://www.mobot.org/gardeninghelp/plantfinder/
Publisher
Missouri Botanical Garden
Year
0
ISBN
 
Description
Basic cultivation details, plant uses, habitat etc for several thousand species of plants, mainly from the temperate zone.
].
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[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
].

Edible Uses

None known

Medicinal

None known

Other Uses

An ethanol extraction of the vegetative parts of the plant is an effective insecticide[
1667
Title
Rhododendron Species and Their Uses with Special Reference to Himalayas - A Review
Publication
Assam University Journal of Science & Technology: Biological and Environmental Sciences, Vol 7 Number 1 pp 161-167, 2011
Author
Bhattacharyya D.
Publisher
 
Year
2011
ISBN
0975-2773
Description
A useful breif guide to the uses of Rhododendron species in the Himalayas
].

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[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
]. 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[
78
Title
Propagation of Trees, Shrubs and Conifers.
Publication
 
Author
Sheat. W. G.
Publisher
MacMillan and Co
Year
1948
ISBN
-
Description
A bit dated but a good book on propagation techniques with specific details for a wide range of plants.
].
Cuttings of half-ripe wood, August in a frame[
78
Title
Propagation of Trees, Shrubs and Conifers.
Publication
 
Author
Sheat. W. G.
Publisher
MacMillan and Co
Year
1948
ISBN
-
Description
A bit dated but a good book on propagation techniques with specific details for a wide range of plants.
].
Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2023-02-03. <temperate.theferns.info/plant/Rhododendron+thomsonii>

Add a Comment:

If you have any useful information about this plant, please leave a comment. Comments have to be approved before they are shown here.