In this case, it's about one of the things that many people find odd about AD&D, how Druids would have to fight other Druids at higher levels. Where did this idea come from? Apparently not reality, though I'm not an expert on Druidic folklore.
But that combat happens in an old Shadow novel, #190, the Circle of Doom, about a group of modern day Druids (kinda).
Reaching to a tree that fringed the nearest monolith, the hooded leader plucked away a small bough. He advanced to the fire, dipped the branch of evergreen into a cauldron that bubbled on the flames. When he raised the bough, it was dripping, and its color was that of gold!
"Who holds the golden bough," declared the Hood in his deep, harsh voice, "shall be master. Let anyone who challenges such authority step forward and wrest the bough from the hand that bears it!"
There were no takers from the crowd of Hoods. Either they feared their
chief, or were satisfied with his leadership.
Later the Shadow does fight with the head druid for leadership of the circle. Was the idea invented just for that scene? Or did the author pick it up somehwere?