The role of hybridization (crossing or mating of two plants) in plant speciation (species evolution) has fascinated generations of botanists and evolutionary biologists. Significant progress in understanding this topic has been made recently by cross-disciplinary studies combining quantitative trait locus (QTL) mapping, comparative genomics, ecological fieldwork, chip-based gene expression analysis, and genetic analysis of specific candidate adaptive traits and the genes that encode them. The combination of these approaches has allowed evolutionary biologists to revisit long-standing hypotheses and controversies regarding the role of hybridization in plant evolution, and conceptual developments fueled by this work are beginning to transform our view of how plant species are formed and maintained.