The BOP clade (sometimes BEP clade) is one of two major lineages (or clades) of undefined taxonomic rank in the grasses (Poaceae), containing more than 5,400 species, about half of all grasses. Well-known members of this clade include rice, some major cereals such as wheat, barley, oat, and rye, many lawn and pasture grasses, and bamboos. Its sister group is the PACMAD clade; in contrast with many species of that group who have evolved C4 photosynthesis, the BOP grasses all use the C3 photosynthetic pathway.