Well there are some people on here who are good on their plants and might chime in on good areas/authors/websites to look at, and of course google/amazon - but also check out some good book stores (not just a retail book store - meaning you want a store clerk who knows their books and such).
Also look in on another website/forum - backpackers.com. There are posts on there about this kind of stuff and where I want you to go and find is the super moderator, bpbikes. He knows his plants/trees like you would not believe - I bet he would have some suggestions especially for a manual to use in the field. He might remember me - I am still on there but haven't been there in a while plus am on a bicycling site he mods as well, I am on those as Tude.
Personally I am interested in the mushrooms and am looking at getting myself going on that. Good luck!
