Knew I'd read it somewhere....this is from Wikipedia though.
"There have been famous episodes of inebriation of humans from consuming toxic honey throughout history. For example, honey produced from nectar of Rhododendron ponticum (also known as Azalea pontica) contains alkaloids that are poisonous to humans but do not harm bees.[34] Xenophon, Aristotle, Strabo, Pliny the Elder, and Columella all document the results of eating this "maddening" honey.[35] Honey from these plants poisoned Roman troops in the first century BC under Pompey the Great when they were attacking the Heptakometes in Turkey. The Roman soldiers became delirious and nauseous after eating the toxic honey, leading to an easy defeat.[36][37]
Honey produced from the nectar of Andromeda flowers contains grayanotoxins which can paralyze the limbs, and eventually the diaphragm and result in death.[34][38] Honey obtained from Kalmia latifolia, the calico bush, mountain laurel or spoon-wood of the northern United States, and allied species such as sheep laurel (Kalmia angustifolia) can produce sickness or even death.[34][39] The nectar of the "wharangi bush", Melicope ternata, in New Zealand also produces toxic honey, and this has been fatal.[40] The dangers of toxic honey were also well-known among the Pre-Columbian residents of the Yucatán Peninsula, though this was honey produced by stingless bees, not by honey bees which are not native to the Americas.[41] Bee nectar collection from Datura plants in Mexico and Hungary, belladonna flowers, henbane (Hyoscamus niger) plants from Hungary, Serjania lethalis from Brazil, Gelsemium sempervirens from the American Southwest, and Coriaria arborea from New Zealand[42] can all result in toxic honey,[43] as can honey made from other toxic plants such as oleander.[44] Narcotic opium honey has also been reported from honey made in areas where opium poppy cultivation is widespread.[45]"
http://en.wikipedia.org/wiki/Bees_and_toxic_chemicals
cheers,
M