Herbalism ?

[Bama]

I am looking for a good book on edible or medicinal plants,any sugestions ? I started to try a quick search and realized that I was'nt sure what to search for, herbalism or botany. Any help will be appreciated.
I am trying to build a good survival library. Can anyone give me a list of books concidered required reading to keep on hand. Thanks again.
Edit: I should have said material to keep on hand or pack in bob, not a home library. A list of reference books or materials to use on the go

[Karen]

I really like Rodale's Illustrated Encyclopedia of Herbs