This book covers a topic of current interest in flora, and it can be considered as a specialized work that will not go out of date for a long time. This book provides new insights into the area of plant taxonomy with respect to xeric conditions. This area, being a hostile and harsh climate, has been neglected for the comprehensive and scientific study point of view. This book is thus a contribution of more than 10 years exploration and collection of plant specimens from the whole study area.