"[Plin. Nat. 24.53.] - THE RHODODENDRON: ONE REMEDY.
The rhododendron has not so much as found a Latin name among us, its other names being “rhododaphne” and “nerium.” It is a marvellous fact, but the leaves of this plant are poisonous to quadrupeds; while for man, if taken in wine with rue, they are an effectual preservative against the venom of serpents. Sheep too, and goats, it is said, if they drink water in which the leaves have been steeped, will die immediately.”
(The Natural History. Pliny the Elder. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855.)