Gentry's Rio Mayo Plants. The Tropical Deciduous Forest and Environs of Northwest Mexico

Abstract

Along with some of my students and friends, I had the pleasure twice to visit this Rio Mayo region and adjacent areas via the kind courtesy of co-author Thomas R. Van Devender, who carefully pointed out all the major constituents of the various vegetation zones of vegetation. I hadnt felt as botanically inept and frustrated with a flora since I first set foot on the Chihuahuan Desert's Cuatro Cienegas Region in Coahuila, Mexico, in the 1960fs. These Rio Mayo trips forced me to reread Dr. Howard Scott Gentry's original book (1942). The fascination with the region is contagious. Gentry's accounts of 1933-1939 in poetic style and picturesque description are now more vividly appreciated. He was the first botanist to seriously explore the Rio Mayo drainage of desertic lowland plains and thorn forests and above. In the 27 months he was there, he collected 3200 numbers representing 1276 species and varieties. His annotated listing (Part 2) describes eight new species and one new variety, including five agaves and two cacti. Also, 66 Gentry collections have been newly described by other authors, all but 15 by Paul C. Standley. The new volume carefully updates, in the same format, Gentry's original account. The authors review and enlarge upon the vegetation and gazetteer via new description, photographs and specimens. Each entry of the burgeoning plant list includes not only the scientific name and classification, but also common names (in English, Spanish, and three native tongues, Guarijio, Mayo and Pima), local and overall distribution, representative documenting specimens, habitats and brief descriptions as to morphology, ecology, ethnology and ethnobotany. The amount of information provided accredits this book as a most valuable and comprehensive reference work. With some collections still in the hands of experts to be determined or newly described, the known flora boasts some 2825 taxa, more than doubling Gentry's original account. There are the 81 new taxa (Gentry 1 942); at least 40 additional taxa based on types and paratypes before the intensive collecting for the present book in the 1970's, many based still on Gentry's own collections; 54 more during the Rio Mayo revision; and 24 still in the process of being described, yielding a total of nearly 200 new taxa for this species rich diverse region, about 7% of the total flora. Shortcomings are few, but identification keys would greatly enhance the use of book. The pull-out map is black and white (in my copy) instead of the advertised color map. This book is a must for all students of Mexican botany, no doubt to be referred to innumerable times. It begs for another update several years from now.