This study presents genome assemblies of 11 bamboo species, revealing insights into the evolution of subgenome dominance in polyploid plants. The bamboo system includes diploid (herbaceous) and tetraploid/hexaploid (woody) species, with 11 chromosome-level de novo genome assemblies and 476 transcriptome samples. The woody bamboo subgenomes show remarkable karyotype stability, with parallel subgenome dominance in the two tetraploid clades and a gradual shift in the hexaploid clade. Allopolyploidization and subgenome dominance have shaped the evolution of tree-like lignified culms, rapid growth, and synchronous flowering in woody bamboos. The study highlights the role of subgenome dominance in genome evolution, including its dependence on genomic context and ability to switch dominance over time. Polyploidy is a major evolutionary force, and subgenome dominance plays a key role in species adaptation and diversification. The study provides insights into the evolution of subgenome dominance in ancient polyploid systems, including the impact of polyploidization on genomic rearrangements and gene expression. The results suggest that subgenome dominance is more dynamic in hexaploid bamboos, with a shift from C to A subgenome dominance in PWBs. The study also identifies genomic changes underlying unique traits in woody bamboos, including lignin biosynthesis and rapid growth. The findings contribute to understanding the genomic basis of evolution and adaptation in polyploid plants.This study presents genome assemblies of 11 bamboo species, revealing insights into the evolution of subgenome dominance in polyploid plants. The bamboo system includes diploid (herbaceous) and tetraploid/hexaploid (woody) species, with 11 chromosome-level de novo genome assemblies and 476 transcriptome samples. The woody bamboo subgenomes show remarkable karyotype stability, with parallel subgenome dominance in the two tetraploid clades and a gradual shift in the hexaploid clade. Allopolyploidization and subgenome dominance have shaped the evolution of tree-like lignified culms, rapid growth, and synchronous flowering in woody bamboos. The study highlights the role of subgenome dominance in genome evolution, including its dependence on genomic context and ability to switch dominance over time. Polyploidy is a major evolutionary force, and subgenome dominance plays a key role in species adaptation and diversification. The study provides insights into the evolution of subgenome dominance in ancient polyploid systems, including the impact of polyploidization on genomic rearrangements and gene expression. The results suggest that subgenome dominance is more dynamic in hexaploid bamboos, with a shift from C to A subgenome dominance in PWBs. The study also identifies genomic changes underlying unique traits in woody bamboos, including lignin biosynthesis and rapid growth. The findings contribute to understanding the genomic basis of evolution and adaptation in polyploid plants.