Yetman and his coauthors cover the saguaro’s biology and its absurd arithmetic — it takes decades to reach a few inches, a hundred and fifty years to full height, thousands of seeds a year of which almost none survive — plus the nurse trees it needs to start, the bats and doves and woodpeckers that depend on it, and its exact range, which is smaller than most people think. Then there’s the human history: The Tohono O’odham harvest and the wine ceremony that begins their year, and the plant’s slide into being a cartoon shorthand for the whole American West. It’s all academic until you meet one in person; I was recently visiting a friend, who introduced me to a foot-high saguaro he’d planted himself. That little guy represents countless of generations of success.