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Ericaceae FAMILY

Rhododendron thomsonii

Rhododendron thomsonii

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Medicinal
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Safety & 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 Description

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. ].

Habitat & Origin

Origintemperate
Native RangeE. Asia - Himalayan regions of China (Xizang), northern India (Sikkim, Arunachal Pradesh), Nepal, Bhutan
HabitatMixed 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. ].