San Bruno Mountain, located in the center of the San Francisco Bay Area, is a four-square-mile global treasure—a natural preserve touted by biologist E. O. Wilson as one of the world’s rare biodiversity hot spots. Bathed in fog and wind and preserved from destruction by the fierce work of local conservationists, this mountain offers visitors a glimpse of what San Francisco looked like before colonization. Drawing on years of visits, observations, and research to offer a comprehensive flora of San Bruno Mountain and its endangered species, conservationists Doug Allshouse and David L. Nelson help us understand this unique and precious place from the point of view of the plants in this one-of-a-kind field guide. Detailing a total of 528 plant species (among them 316 natives), the authors also delve into the history of this living, changing habitat at the southern edge of San Francisco. The birds, butterflies, reptiles, geology, climate, dynamic changes, and political history of the preserve also feature in San Bruno Mountain. Even locals who have enjoyed hiking and viewing the mountain for years will be astonished at this book’s revelations about the diversity and importance of this wild place.