A Preliminary Revision of the North American Species of Cactus, Anhalonium, and Lophophora

"A Preliminary Revision of the North American Species of Cactus, Anhalonium, and Lophophora" by John Merle Coulter is a scientific study from the 1800s that sorts and groups cacti from North America, especially types known as Cactus, Anhalonium, and Lophophora. The book seeks to create a system for understanding the changes within these plant groups, which inspired more research and gathering of plant samples. Starting with a letter from the U.S. Department of Agriculture, it tells how the revision project began, which involved collecting plants and making observations in the field; it points out struggles in studying cacti, like not having enough flower or fruit samples, and it describes how the author worked with others to organize the information collected. The early revisions of the plants give clues about the different structures and growth patterns, guiding future research by botanists in plant classification.