The arborescent gymnosperms are the most prevalent trees in one-third of the world's forests, and have dominated the Earth's forest ecosystems through much of evolutionary time. They encompass over 70 living genera and nearly 700 species of evergreen conifers and related trees, and include the largest and longest-lived organisms on this planet. This two-volume treatise provides detailed descriptions of each genus based on first-hand surveys of their structure, adaption, ecology, function and development. It also incorporates evidence from molecular studies, palaeobotany and environmental data to provide a holistic understanding of their overall evolution and diversity. Covering the world's temperate and tropical forests, Volume 1 principally focuses on Northern Hemisphere genera while Volume 2 covers those with a predominantly Southern Hemisphere range. Together, the set provides a comprehensive, global reference for researchers in palaeobotany, plant science, geobiology, evolutionary biology, ecology and plant genetics, as well as arboriculturists and conservation managers.