The definitive story of cannabis, from its evolution and biological characteristics to its role in human history. In this engaging natural history, Rob DeSalle offers a look into the biological world from the perspective of the cannabis plant. A close relative of hop with a surprising botanical lineage, cannabis has a unique life cycle, has evolved along pathways for over four hundred combinations, and produces about a thousand different chemicals stored in its tissues—some of which form the basis of its renowned psychoactive properties. With his scientific perspective on this well-known and controversial plant, DeSalle examines its taxonomy, systematics, evolution, human physiology, and neurobiology, as well as cultural issues. He discusses the plant’s complex reproductive strategies, explores ancient relationships between insects and cannabis from South Asia, and provides a multifaceted cultural history from the earliest evidence of cannabis use over two thousand years ago to current discussions on legalization. Extensively researched and illustrated by Patricia J. Wynne, this is a vital resource for cannabis enthusiasts and anyone curious about the science behind this famous "weed."