Rhododendron yakushuminum Nakai, Ericaceae. Cultivar 'Grumpy'. Distribution: Yaku-shima an island off the south coast of Japan. Discovered early 1900s, introduced to UK in 1934. No medicinal value but the leaves of rhododendrons are very poisonous, due to a toxic resin called grayanotoxin. This is also present in the nectar; sucking it from the flowers or eating two leaves, causes serious illness - stomach upsets, gastric haemorrhage, aspiration pneumonia, renal tubular damage and liver damage. Diarrhoea, vomiting, anorexia, weakness, incoordination, stupor and often death (Illinois Veterinary library website, 2013). Other websites extol the virtues of tea from R caucasicum, attributing the longevity of the people of Georgia to regular use. Honey from pollen of R. luteum is thought to have poisoned Xenophon's army in 401BC and Pompey's army in his campaign against King Mithridates of Pontus in 66 BC. Honey from another rhododendron, R. afghanicum, poisoned Alexander the Great's army in 327 BC.

No medicinal value but the leaves of rhododendrons are very poisonous, due to a toxic resin called grayanotoxin. This is also present in the nectar; sucking it from the flowers or eating two leaves, causes serious illness - stomach upsets, gastric haemorrhage, aspiration pneumonia, renal tubular damage and liver damage. Diarrhoea, vomiting, anorexia, weakness, incoordination, stupor and often death (Illinois Veterinary library website, 2013). Honey from pollen of R. luteum is thought to have poisoned Xenophon's army in 401BC and Pompey's army in his campaign against King Mithridates of Pontus in 66 BC. Honey from another rhododendron, R. afghanicum, poisoned Alexander the Great's army in 327 BC. However this may both have been due to Oleander.