Tonight I went to see the movie Sherlock Holmes with family for Christmas. The entire movie was a quite macabre spectacle of science vs. superstition and magic. What as a particular interesting piece of the plot was a reference in the movie to toxic honey induced by the the collection of bees of pollen from the rhododendron, so called toxic honey. This is the plant that permitted Lord Blackwood to appear without a pulse and seem as though he was dead. The reference reminded me of the famous passage from Xenophon in which he describes the retreat of the 10,000 through the Pontus region of Turkey, where the rhododendron grows wild.
Here, generally speaking, there was nothing to excite their wonderment, but the numbers of bee-hives were indeed astonishing, and so were certain properties of the honey. The effect upon the soldiers who tasted the combs was, that they all went for the nonce quite off their heads, and suffered from vomiting and diarrhoea, with a total inability to stand steady on their legs. A small dose produced a condition not unlike violent drunkenness, a large one an attack very like a fit of madness, and some dropped down, apparently at death's door. So they lay, hundreds of them, as if there had been a great defeat, a prey to the cruellest despondency. But the next day, none had died; and almost at the same hour of the day at which they had eaten they recovered their senses, and on the third or fourth day got on their legs again like convalescents after a severe course of medical treatment. (taken from Daryn's translation on Project Gutenberg here)
Apparently the agent that is responsible for the poisoning effect is grayanotoxin. As to how it works, there is an interesting article on the Federal Food and Drug Administration website here.