Brazilian-Venezuelan sub-region covers almost all basin of Amazon River (excepting highland areas of Andes), in the south the upper half of basin of Paraná River and in the north the basin of Orinoco River. This area belongs to the botanically richest areas in the world. The amount of species strongly overreaches the number of 50.000. About one half of all genera are endemic. Endemism of species could be even bigger locally, especially in highland areas. Some authors classify this sub-region for more detail into Venezuelan-Guiana, Amazon and Brazil area.