Collections of preserved plant specimens, known as herbaria, have existed for nearly five centuries. These pressed and labeled plants have been essential resources for scientists, allowing them to describe and differentiate species and to document and research plant changes and biodiversity over time--including changes related to climate. Maura C. Flannery tells the history of herbaria, from the earliest collections belonging to such advocates of the technique as sixteenth-century botanist Luca Ghini, to the collections of poets, politicians, and painters, and to the digitization of these precious specimens today. She charts the growth of herbaria during the Age of Exploration, the development of classification systems to organize the collections, and herbaria's indispensable role in the tracking of climate change and molecular evolution. Herbaria also have historical, aesthetic, cultural, and ethnobotanical value--these preserved plants can be linked to the Indigenous peoples who used them, the collectors who sought them out, and the scientists who studied them. This book testifies to the central role of herbaria in the history of plant study and to their continued value, not only to biologists but to entirely new users as well: gardeners, artists, students, and citizen-scientists.