Tetramerium is a genus of plants belonging to the family Acanthaceae. It is found in the Americas,[2] ranging from the southwestern United States to Bolivia,[1] especially in tropical dry forests.[3] Christian Gottfried Daniel Nees von Esenbeck first described the genus in 1846 after collecting two species (T. polystachyum and T. nervosum) on the journey of HMS Sulphur.[3][4]