Snakes have always gotten the short end of the stick. No other animal has quite the same reputation for sneakiness, cunning, and general deadliness. No other animal makes you think "Satan" or "devil" quite as easily. Monkeys even have a special cry meaning "Look out! Snake!"
So it's natural that one of the story's wiliest characters—the traveler with the "serpentine staff"—would have a staff shaped like this wily animal (36).
But something really, really weird happens later on. The traveler decides to make a new staff, plucks a new stick, and begins "to strip it of the twigs and little boughs, which were wet with evening dew. The moment his fingers touched them, they became strangely withered and dried up" (38).
Two things worth noting here. First, never, never invite this man to a flower show. And second, the natural world—or God's good creation, as the Puritans would have it—can't stand this guy. Like the snake in the Garden of Eden, he's as destructive as they come.