Abstract: We review and summarize the progress of studies of LEAFY genes. Sequence comparative analysis of the orthologs of genes isolated from a wide variety of plant species showed high similarity in coding sequence at the nucleotide and amino acid levels but different copy numbers, especially in diploid angiosperms. Orthologous genes, however, have variant expression patterns in different plants. Phylogenetic analysis of the predicted protein sequences of the orthologs supported the currently accepted theory of phylogenetic partnerships of plant species. The information summarized here is helpful not only for better understanding the mechanisms of plant flowering but also for further promoting studies of the evolution of flowering plants.