In an article titled Scents of Place in the May June 2000 edition of Saudi Aramco World Tim Mackintosh-Smith describes visiting frankincense groves. He remembers Herodotus, who claimed the groves were guarded by "vicious flying snakes".
Later on his guide tells him, "Watch out for snakes."
I remembered Herodotus. "Not flying ones...?"
"Yes. They jump out of the samur trees."
Herodotus, I thought, I shall always give you the benefit of the doubt.
I always remember that as an illustration of how some legends do have a basis in fact.