Book excerpt: Towering over deserts, arid scrublands, and dry tropical forests, giant cacti grow throughout the Americas, from the United States to ArgentinaÑoften in rough terrain and on barren, parched soils, places inhospitable to people. But as David Yetman shows, many of these tall plants have contributed significantly to human survival. Yetman has been fascinated by columnar cacti for most of his life and now brings years of study and reflection to a wide-ranging and handsomely illustrated book. Drawing on his close association with the Guarij’os, Mayos, and Seris of MexicoÑpeoples for whom such cacti have been indispensable to survivalÑhe offers surprising evidence of the importance of these plants in human cultures. The Great Cacti reviews the more than one hundred species of columnar cacti, with detailed discussions of some 75 that have been the most beneficial to humans or are most spectacular. Focusing particularly on northwestern Mexico and the southwestern United States, Yetman examines the role of each species in human society, describing how cacti have provided food, shelter, medicine, even religiously significant hallucinogens. Taking readers to the exotic sites where these cacti are foundÑfrom sea-level deserts to frigid Andean heightsÑYetman shows that the great cacti have facilitated the development of native culture in hostile environments, yielding their products with no tending necessary. Enhanced by over 300 superb color photos, The Great Cacti is both a personal and scientific overview of sahuesos, soberbios, and other towering flora that flourish where few other plants growÑand that foster human life in otherwise impossible places.