As an everyday herb lover the only book I know of on this subject is "Healing Power of Rainforest Herbs: A Guide to Understanding and Using Herbal Medicinals" by Lesley Taylor, I've seen the book at a friends, although I don't yet own a copy, its a lovely book and definitely one worth checking out.
The synopsis on Amazon for this book says [This work uses handy tables to list the medicinal properties of each plant and pinpoints appropriate treatments. Rainforests contain an amazing abundance of plant life - just two and a half acres of the Amazon rainforest are believed to house approximately 900 tons of plants. What's most exciting is that scientists and researchers have only just begun to uncover the medicinal qualities of these plants - treasures of nature that offer new approaches to health and healing. "The Healing Power of Rainforest Herbs" is a valuable guide to these herbs and their uses. Detailing more than fifty rainforest plants, "The Healing Power of Rainforest Herbs" is the result of years of extensive research by naturopath, Leslie Taylor. In it, she explains the medicinal properties of each herb and the natural chemicals involved, as well as preparation instructions. The author has, also, included the history of the herbs' use by indigenous peoples and their current usage by natural health practitioners throughout the world. Helpful tables provide a quick guide for choosing the most useful plants for specific ailments.
Illustrations of plants and recipes for herbal remedies complete the wealth of information found in this resource. "The Healing Power of Rainforest Herbs" is a unique book that offers a blend of ancient and modern knowledge in an accessible reference guide. It incorporates the healing practices of shamans with scientific research for anyone seeking to discover the medicinal secrets of the rainforest. ]
I have to agree with the reviewer on Amazon it is a beautiful book, lovely photos and the author writes with a passion about the herbs. Maybe one of the more knowledgeable and herbally qualified people amongst the forum users will be able to suggest other books that have safety and doese related information or a more 'scientific' approach to the subject. But as a lay person I can recommend the book above.