Combining insights from observation, experimentation, and theory, The Origin, Expansion, and Demise of Plant Species offers a broad overview of species as dynamic entities that arise, have unique evolutionary histories, and ultimately go extinct. It begins with a review of species concepts and the exposition of a new concept; it then addresses plant speciation, the expansion of species from their narrow centers of origin, intraspecific differentiation, and contact zones between differentiated population systems. Special attention is given to the breakdown of cohesion among populations by reproductive and spatial barriers. Also, the ecological and genetic properties of small populations and fragmented population systems are discussed with a focus on the role of hybridization in the demise of species. It ends with an exploration of the longevity of species and the tempo of diversification, contrasting different groups of plants in these respects as well as in rates of chromosomal differentiation.This book provides a new synthesis of evolutionary biology and ecology. It examines species from their origins, then follows them through their expansion, differentiation and loss of cohesion, and decline and extinction. The stages in the lives of species are viewed through ecological and genetic theory, and topics typically addressed independently are woven into a continuous fabric. As the first synthetic treatment of the stages through which plant species pass, this book is very useful for botanists, evolutionary biologists, conservation biologists, as well as all curious students of the biological sciences.