Plant Systematics, or taxonomy, stands out in modern plant biology for its rich history and ongoing relevance. Originating other botanical disciplines, it addresses the fascinating diversity of plant species on Earth, acting as a unifying force in biology. It integrates data from fields like molecular biology, biochemistry, comparative phytochemistry, and electron microscopy to build a framework for plant classification. Without the nomenclature system provided by plant taxonomy, comparative references to plant names would be impossible. The third edition of Plant Systematics responds to recent advancements and discoveries, presenting current principles and practices of plant taxonomy and contemporary classifications while describing significant families and groups of vascular plants. It provides a comprehensive and up-to-date synthesis of this dynamic field, covering new topics such as phenetics, cladistics, vicariance biogeography, and expanded biochemical systematics. Designed for undergraduate students, the book's chapters are independent, allowing instructors flexibility in sequencing topics. It also aims to stimulate serious amateurs, teachers, and professionals who use plant classifications and taxonomic information. The book is divided into fourteen chapters and four appendices, covering traditional and modern aspects of plant systematics.