Quite specific, I know. Further information as I seem to recall it. The man was an archaeologist on the way to a dig in the amazon. His plane crashed, and he found himself in a tribe where he was one of the few men. At some point, he tries to leave, and becomes ensnared by a plant that transforms him into a woman. Things happen (there's a reason why I wanted to reread the story), that lead to her becoming queen of that tribe, and more accurately, queen of that planet she landed on. There's a portal back to earth that points to his/her old apartment, and she becomes quite a celebrity on Earth.