If you're also interested in ethnobotany and more specifically the use and history of psychoactive plants I can highly recommend this tome: Ratsch,C - Encyclop

If you're also interested in ethnobotany and more specifically the use and history of psychoactive plants I can highly recommend this tome: Ratsch,C - Encyclopedia of Psychoactive Plants Unlike many other books on this subject matter, it is very well researched and referenced, but at the same time also contains personal anecdotes and experiences from the author himself.