Polyploidization contributes to the forms, heights, and species richness of plants

Whether plant life form influences the long-term persistence of polyploid lineages remains an important unresolved question in plant evolution. Previous studies have suggested that perennial herbaceous plants harbor higher proportions of neo-polyploids, yet comprehensive phylogenetic validation across paleopolyploid lineages using genomic data remains limited. The rapid accumulation of plant genome sequences, particularly from horticultural and agricultural species, provides an unprecedented opportunity to investigate the evolutionary relationships among polyploidization, plant growth form, and plant stature across seed plants. Here, we analyzed 351 seed plant genomes, including major cereals, vegetables, fruits, and their wild relatives, to investigate the long-term evolutionary associations between paleopolyploidization and plant phenotypic diversity. Phylogenetically informed comparative analyses showed that lineages experiencing more paleopolyploidization events were significantly more likely to exhibit herbaceous rather than woody growth forms. We further found that paleopolyploidization frequency was negatively associated with plant height across seed plants after accounting for phylogenetic relatedness. In addition, evolutionary rates, estimated using synonymous substitution rates (Ks), were associated with paleopolyploidization, plant growth form, and species richness. Herbaceous species exhibited higher Ks values than woody and vine species, and plant families with higher evolutionary rates tended to contain more species. Together, these findings provide a phylogenetically informed evidence that paleopolyploidization is closely associated with plant growth form, plant stature, and evolutionary rate, offering new insights into the long-term evolutionary consequences of genome duplication in seed plants.