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Jun 15th, 2021 (Article in newsletter, June 2021)

Book review: Field Guide to the Flora of the San Gabriel Mountains

Barbara Eisenstein

In his Field Guide to the Flora of the San Gabriel Mountains, Orlando Mistretta pulls together both historical and current information on what is growing in the 700,000 acres of mountainous terrain that form the backdrop of the Los Angeles Basin. Although much is known about the plants of the San Gabriel Mountains, Mistretta’s field guide is a comprehensive compilation, a sort of one-stop-shop flora of a region that is both remote and sometimes inaccessible, while also being right next to one of the world’s most densely populated urban centers.

The book contains diagnostic keys for identifying plants of our local mountains. The keys are scientific and require a good knowledge of botanical terminology. Each entry includes a taxonomical treatment, a description of plant characteristics, abundance, habitat, elevation, soil type, and specific collection locations. In addition, there is a reference to a single herbarium voucher for each taxa. Viewers can access these herbarium vouchers and sheets on the California Consortium of Herbaria Database (CCH2 portal). Though this handy field guide does not contain drawings and photographs of the plants, this is not a handicap given the abundance of online resources such as Jepson e-Flora, Calflora, and CalPhotos.

An introduction with beautiful glossy pictures precedes the flora. There is a general description of the San Gabriels, along with maps showing the project location and border. Hikers of these mountains will recognize in a clear, stylized map their favorite canyons and landmarks from both the coastal and desert ranges. Mistretta includes a brief historical account including quotes from European-American naturalists and botanists. His passion for these mountains is apparent in his photographs and his writing.

Although this field guide is most appropriate for botanists and native plant experts, hobbyists will find much of interest in it, as well. For example, while I, a non-expert, may not have the knowledge or patience to key out a complete unknown, the guide will be very helpful in determining the exact species and even subspecies of plants that I can identify down to the family or genus level.

Another way that this book will be helpful is in locating specific plants in the San Gabriels. It is true that iNaturalist and CalFlora can yield significant information on plant sightings; nonetheless, Mistretta’s guide provides additional information on plant characteristics and ecology, and historical background through the herbarium voucher references.

Let me give a specific example of how this guide can be helpful to hobbyists as well as experts.  I truly love the subtle and beautiful California peony (Paeonia californica), and am excited to see it bloom in the wild. Consulting the guide, I learn that it is common in shrublands below 1,000 meters. It can be found on the coastal slopes from the western to the eastern edge of the San Gabriel Mountains. The field guide informs me that it was collected by W. Wisura, 5119. According to the CCH2 portal Wisura collected this plant on April 3, 1998, on Swarthout Canyon Road south of Lone Pine Canyon Road. in San Bernardino County. The guide provides me with background on the plant, so I can search for it in known locations, as well as seek it out in other likely locals. So, armed with information from Mistretta’s field guide, Calflora, and iNaturalist, I guess I better get out there to look for this beauty!

You too will want to get a copy of the Field Guide to the Flora of the San Gabriel Mountains before the next wildflower season. If you have some favorite plants that you wish to visit, consult this authoritative and comprehensive manual to begin your search with a strong background. If you are just interested in the plants you see on your hikes, this book will expand your knowledge and understanding. And if you are a botanist or naturalist, this book is definitely something you will want in your library.

To purchase the book: You can purchase Orlando's book from the California Botanic Garden (CalBG). There are two options:
a) Order from the Online Store (click here) — you will need to pick up the book from CalBG.
b) If you need to book to be mailed, please contact the CalBG librarian to arrange purchase and mailing (click here).

For the past fifteen years Barbara Eisenstein has run a local volunteer stewardship program, Friends of South Pasadena Nature Park. She is on the board of the San Gabriel Mountains Chapter of the California Native Plant Society and was horticulture outreach coordinator at the California Botanic Garden in Claremont. She is the author of Wild Suburbia: Learning to Garden with Native Plants.Visit her website at

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