Plant paleopolyploidy

The plant lineage, and specifically angiosperms, have a genomic history of repeated whole genome duplication events. This pattern of changing their ploidy level (or number of copies of their genome) is something that happens frequently today, and many domesticated crop plants have been selected with various ploidy levels. While the mechanisms are unknown that permit polyploidy is some lineages such as plants, and not as frequently in others such as mammals <ref=mammal>There is a case of a tetraploid rodent: Gallardo. 2006. Molecular cytogenetics and allotetraploidy in the red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae) Genomics. 88:2, 214-221. doi:10.1016/j.ygeno.2006.02.010</ref>.

Phylogenetic tree of plant species with sequenced genomes, with ancient whole genome duplications marked. Grass species are the only sequenced representatives of the monocot plant lineage, and all published eudicot genomes come from species in the rosid family.