The definitive treatment of the trees and tree-like plants of Sonora, a remarkably diverse and biologically important region, ranging from some of the driest and hottest areas in North America to cool, temperate woodlands and the northernmost tropical regions in the New World. The majority of the trees in this semi-arid region are at their northern limits in the Americas in this state and many range to South America. Thus, this book will be important to biologists in regions well outside of the area covered. Felger is the recognized expert in the area, and the book contains an enormous body of information nowhere else obtainable. The introductory chapter contains biotic and climatic information and an analysis of the geographical distributions of the trees of a state that is poorly known biologically. Two hundred eighty-five species of native and naturalized trees are covered, featuring extensive identification keys and illustrations, most of them newly produced for this book. The descriptive species accounts include common names, indigenous names, and synonyms, detailed botanical descriptions, ecological and geographic data, geographic ranges, natural history, economic uses, and, in many cases, other information such as horticultural uses and conservation status.