Author; David Allen Sibley
Here is a little piece from the book so you can see the main points.
This book covers the identification of 668 native and commonly cultivated trees found in the temperate areas of North America north of Mexico. This includes most of the continental United States and Canada, an area corresponding to the United States Department of Agriculture (U 5 DA) plant hardiness zones 1-8. A color-coded map with a key on the inside front cover illustrates the hardiness zones covered in this guide.
All native trees are included in the species accounts of this book, except those trees found only in southern Florida, which is home to over one hundred native species found nowhere else on the continent. All commonly cultivated species are covered, but the warmest climates in North America have a progressively higher diversity of cultivated trees and fewer of these species
will be found in this guide.
If you are reading this book, you presumably have an interest in the identification of trees, and several tips and suggestions are offered below to help you get started. Just as in learning anything new and complex-
a new language, playing a musical instrument, identifying birds-the key to success is study and practice. The more you look at trees, the more easily you will identify them.
Simply noticing trees as you travel through your daily routine, or spending time at home browsing this or other books about trees, is an excellent way to become familiar with the basic patterns of variation and the common species of trees.
One of the keys to identifying trees at a distance is knowing how to sort the important bits of information from the unimportant ones. The overall size and shape of a tree is usually useful only for the broadest indication of what group it might be in, while the pattern formed by twigs is a very useful identification clue. Getting out in the field and looking at lots of trees is the only way to develop this knowledge, as you will gradually, and subconsciously, begin to understand which elements really distinguish each tree. Looking at the same trees daily throughout the year and noting changes will also provide valuable experience. Taking notes or making sketches of what you see is an excellent learning tool-it forces you to focus on all the aspects of the tree and the act of recording your observations will reinforce what you have observed.
Our brains are very good at pattern-recognition, so this is something that doesn’t take much conscious effort, but it can be helpful to watch for and try to make generalizations. For example, all birches have slender graceful twigs and all poplars have stout stiff twigs. Learning the broader patterns of variation at the group level of trees, rather than species-by-species, can greatly enhance your understanding and enjoyment.
USE MULTIPLE FIELD MARKS
Trees are extremely variable, and no single field mark will ever be sufficient to identify
a tree. You will have to look for multiple features. By using multiple clues, including range and habitat, you can begin to identify trees at a distance without seeing any smaller details, in the same way that experienced birdwatchers identify hawks from a great distance."
Hopefully that will give you a good idea of this book and how great it is.