Oliver Sacks, a well known writer and neurologist, has written a marvelous diary about a trip he took to Oaxaca on a 'fern tour'. Oaxacas diversity, ecologically and culturally, is one of the subjects of this book, Oaxaca Journal. Reading it  before or during a trip to Oaxaca will enhance your experience. Sacks' account is full of interesting tidbits, as well as observations on his tour companions, their guide, the feel of Oaxaca and its environs. It's a charming and well written account of a journey which should interest any traveler, not just those who are interested in botany.