A modern approach to understanding the evolution and diversification of land plants, one of the most exciting areas of plant systematics. It consists of three sections - origin and diversification of primitive land plants; origin and diversification of angiosperms; speciation and mechanisms of diversification - each section corresponding to a major area in plant evolution. In each case, data from molecular, morphological, and paleontological approaches are presented, backed by recent progress and new findings, together with proposals for future research. A guide to the latest in plant systematics, heightening awareness of prospective future problems.