Ash is a beautifully illustrated account of the botanical and cultural faces of the ash tree. The book maps the tree's evolution and geographical spread across the entire Northern Hemisphere over the last 44 million years, and describes the 43 species that grace the planet today. Edward Parker also explores the botany, cultural history, and medicinal uses of the tree, from its significance in ancient Indo-European cultures, to its remarkable properties in treating Alzheimer's disease. In addition he looks at topical issues, such as the devastating effects that the spread of the emerald ash borer beetle and the ash dieback fungal infection are having on Northern Hemisphere forests.