The One Thousand Plant Transcriptomes Initiative sequenced the vegetative transcriptomes of 1,124 plant species, spanning the diversity of Archaeplastida, including green plants, glaucophytes, and red algae. This study provides a robust phylogenomic framework for understanding the evolution of green plants. Analysis of gene family expansions and genome duplications reveals that these events played a key role in the evolution of major innovations in green plants, including the development of vascular tissues, roots, and seeds. The study also highlights the complexity of plant genome evolution, including polyploidy, rapid speciation, and extinction. The findings suggest that large gene family expansions preceded the origins of green plants, land plants, and vascular plants, while whole-genome duplications occurred repeatedly in flowering plants and ferns. The study also identifies the timing of ancient genome duplications and gene family expansions, and shows that these events are closely linked to major evolutionary transitions in green plants. The study provides insights into the genetic changes that underlie the characteristic traits of green plants, and highlights the importance of phylogenomic approaches in understanding the evolution of plant genomes. The study also identifies the key innovations that enabled the colonization and exploitation of novel habitats by plants, and shows how these innovations influenced the evolution of other lineages. The study also highlights the importance of functional genomics in understanding the evolution of plant genomes. The study is a major contribution to the understanding of the evolution of green plants and their genetic diversity.The One Thousand Plant Transcriptomes Initiative sequenced the vegetative transcriptomes of 1,124 plant species, spanning the diversity of Archaeplastida, including green plants, glaucophytes, and red algae. This study provides a robust phylogenomic framework for understanding the evolution of green plants. Analysis of gene family expansions and genome duplications reveals that these events played a key role in the evolution of major innovations in green plants, including the development of vascular tissues, roots, and seeds. The study also highlights the complexity of plant genome evolution, including polyploidy, rapid speciation, and extinction. The findings suggest that large gene family expansions preceded the origins of green plants, land plants, and vascular plants, while whole-genome duplications occurred repeatedly in flowering plants and ferns. The study also identifies the timing of ancient genome duplications and gene family expansions, and shows that these events are closely linked to major evolutionary transitions in green plants. The study provides insights into the genetic changes that underlie the characteristic traits of green plants, and highlights the importance of phylogenomic approaches in understanding the evolution of plant genomes. The study also identifies the key innovations that enabled the colonization and exploitation of novel habitats by plants, and shows how these innovations influenced the evolution of other lineages. The study also highlights the importance of functional genomics in understanding the evolution of plant genomes. The study is a major contribution to the understanding of the evolution of green plants and their genetic diversity.