List of Poaceae genera

Grasses probably originated in the understory of tropical rainforests in the Late Cretaceous, but have since come to occupy a wide range of different habitats.^[3][4] Notably, they are the dominant species in grasslands, open habitats that cover around one fifth of the earth's terrestrial surface.^[3] The C₄ photosynthetic pathway has evolved at least 22 times independently in the grasses; C₄ species are more competitive than C₃ plants in open habitats with high light intensity and warm temperatures.^[5]

The deeper relationships in the family have been resolved by recent molecular phylogenetic work.^[5] This has been translated into a modern classification which divides the grasses into twelve subfamilies and a number of tribes, with large tribes further divided into subtribes.^[1]

Anomochlooideae, Pharoideae and Puelioideae are early diverging lineages containing only a few species. Most of the diversity falls into the two big BOP and PACMAD clades, which each contain roughly half of the family's species. C₄ lineages have only evolved in the PACMAD clade, whereas many lineages in the BOP clade have evolved adaptations to cold climate.

While the higher-level classification of the grasses is now relatively well understood, taxonomic efforts continue at the species and genera level, and with continuing phylogenetic research, a number of names is likely to change.^[6] The list of genera below is therefore likely to evolve with further study.

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