Environmental and specific diversity in the Chihuahuan desert in general, and in the Cuatro Ciénegas Basin in particular, has long been recognized as outstanding. This book provides a global ecological overview, together with in-depth studies of specific processes. The Chihuahuan desert is the warmest in North America, and has a complex geologic, climatic and biogeographical history, which affects today’s distribution of vegetation and plants and generates complex phylogeographic patterns. The high number of endemic species reflects this complex set of traits. The modern distribution of environments, including aquatic and subaquatic systems, riparian environments, gypsum dunes and gypsum-rich soils, low levels of phosphorous and organic matter, and high salinity combined with an extreme climate call for a range of adaptations. Plants are distributed in a patchy pattern based on punctual variations, and many of them respond to different resources and conditions with considerablemorphological plasticity. In terms of physiological, morphological and ecological variability, cacti were identified as the most important group in specific environments like bajadas, characterized by high diversity values, while gypsophytes and gypsovagues of different phylogenies, including species with restricted distribution and endemics.