This visually stunning book presents a white-background approach to capturing the unique flora of Mexico’s Sierra San Pedro Mártir, including many endemic and endangered species, in exquisite photographic detail.

A Guide to the Flora of the Sierra de San Pedro Mártir / Una Guía a la Flora de la Sierra de San Pedro Mártir by Alan Harper, Sula Vanderplank and Jon Rebman. BRIT Press / California Native Plant Society.

The xeric pine-dominated forest of the Sierra San Pedro Mártir in northern Baja California has its own photographic guide. The authors, Alan Harper, Sula Vanderplank and Jon Rebman, present a revolutionary approach for botanical guides, featuring an interesting assemblage of species.

The book presents 235 of the 500 plants reported for the Sierra above 1800 m, including 25 of the 27 plants that are endemic to this mountain range, and 18 other plants endemic to the state of Baja California.

“It was a huge amount of work,” says biologist and photographer Alan Harper, in an exclusive interview, “but I was very thrilled to do something on one of my favorite places in Mexico”.

A man crouches to photograph a plant in what looks like a tent with a white screen on the interior.
Alan Harper at work. Image: Sula Vanderplank.

The book is essentially ‘seamless white photography’ combined with Bruce Kirchoff’s ideas on how to build visual guides, and an interesting flora.

With the aid of volunteers, who took freshly collected plants to the field studio “we were able to photograph them when they’re just in perfect shape,” explains Harper. Several simultaneous flashes were directed at the plant and the background so that it is relatively easy to remove the background in the computer. The result is a set of highly detailed photographs that allow to see the morphological features of the plants against a clear white background. Some of these pages, in my opinion, are beautiful works of art.

A short spiny cactus that, in one photo, does indeed look like a hedgehog curled up.
Echinocereus mombergerianus. Sierra San Pedro Mártir Hedgehog Cactus (endemic to the Sierra). Image from Harper, Vanderplank, and Rebman 2021.

The wonderful, scientific assortment of photos is preceded by five chapters that contextualize it. On the first chapters, symbols and abbreviations are explained, regional maps are presented, and taxonomic names are referred to the latest inventories of the flora of the Sierra. Contributing authors, Gonzalo de León, Hugh Safford and José Delgadillo, provide information on the National Park, the natural fire dynamic of the forest, and the general physiognomy of the vegetation, respectively. Every text in the book is presented in both English and Spanish.

Being fascinated by history and exploration, I especially enjoyed reading the chapter “History and Exploration.” Although the first (1792) written description of the high elevation landscape and the accounts of early explorers are interesting narratives, they are also key to recognize landscape change and how it has been influenced by human practices. Current knowledge of the Sierra San Pedro Mártir suggests that fire suppression and cattle grazing are the main obstacles for the appropriate conservation of the forest.

Stems and flowers of a bright white flower against a white background with a very small central yellow core to the flower.
Leptosiphon melingii. Meling Linanthus (endemic to the Baja California peninsula). Image from Harper, Vanderplank, and Rebman 2021.

On the photographic part of the book, I would just add that a few of the specimens photographed do not do justice to the attractiveness the plants have in the field. The specimen representing Sarcodes sanguinea appears dry and dull, unlike the “bright glowing pilar of fire” described by John Muir. The specimen was probably collected long after emerging from the ground. But for the majority of the species, the photos in the book enhance the plants’ natural appeal. Anyone fond of plants will enjoy looking at these photos. Even grasses, neglected by some botanists, appear interesting in this book.

This book is most valuable for someone acquainted with the place, but even if one never travels to these mountains, it is worth getting to know this noteworthy approach to botanical guides and the flora of this singular sky island.


Harper, A., Vanderplank, S., & Rebman, J. (2021). A guide to the flora of the Sierra de San Pedro Mártir |Una guía a la flora de la Sierra de San Pedro Mártir. ISBN-13: 978-1-889878-64-5. Botanical Research Institute of Texas Press.

Kirchoff, B. K., Leggett, R., Her, V., Moua, C., Morrison, J., & Poole, C. (2011). Principles of visual key construction―with a visual identification key to the Fagaceae of the southeastern United States. AoB PLANTS, 2011, plr005.

Muir, J. (1961). Mountains of California. Natural History Library. Cited in Mackintosh, G. (2003). Nearer My Dog To Thee. A Summer in Baja’s Sky Island. Baja Detour Press. San Diego, California.

SD Natural History Museum (2023). Nat Talk: Flora of the Sierra de San Pedro Mártir. Youtube.

Cover image: samples from the book by Alan Harper.

Spanish translation by Patrick Gibson

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