Recommended reading: Oaxaca Journal by Oliver Sacks
In pursuit of ferns, Sacks and friends travel to Oaxaca, Mexico -- a hot spot for pteridophytes, with at least 690 species. His journal is entertaining and thought-provoking. Sacks describes the ferns and the fern-seekers themselves, an interesting bunch as one would expect. He speculates about the societies of the Zapotecs and Aztecs, and the important plants: corn and beans, tobacco, cacao, and plant-derived hallucinogens that may explain some rock art (Sacks the neurologist hints at the possibility of escaping the confines of our mental constructs). Fern-lovers, pre-Colombian Indians and Sacks himself are the the subjects of his continuing exploration of life -- looking for "the relationships and activities, the practices and skills, the beliefs and goals, the ideas and dreams, that make for a full human life."