I've seen numerous posts in this forum regarding personal education in botany in which I too have an iterest. I am always looking for good, comprehensive identification books and manuals to give me a better understanding about plants I run into. Douglas Justice mentioned the Manual of Woody Landscape Plants by Michael Dirr in the thread entitled "Dogwood Trees that aren't bloominig" in Plants/Dogwoods, which looks like an excellent resource. I found two other books by Dirr that also sound good: Dirr's Hardy Trees and Shrubs: An Illustrated Encyclopedia, Dirr's Trees and Shrubs for Warm Climates: An Illustrated Encyclopedia. What other books do you find helpful?