Here are some sources for Around the World in 80 Trees and Around the World in 80 Plants. It isn’t an exhaustive list; if you can’t find what you’re looking for, please contact me so I can help!
General Bibliography
I have used these sources repeatedly for useful background on many trees and plants.
Online Resources
The online services I often consulted for Around the World in 80 Trees and Around the World in 80 Plants.
Individual Species References
Species-specific references for each species featured in Around the World in 80 Plants, listed in alphabetical order of scientific name.