The Pampa plain is a geomorphological domain that occupies a vast proportion of the southern plains of South America. It covers approximately 540,000 km2, between 29–38°S and 57–67°W. From a geological point of view, six aeolian units were described based on the nature of the Late Quaternary aeolian deposits, landforms, and their geological-structural settings. From a vegetational point of view, eight vegetation units belonging to two phytogeographic provinces were described based on current spontaneous terrestrial vegetation. In this chapter, the spontaneous terrestrial vegetation of the two phytogeographic provinces and their vegetation units that completely cover the Pampa plain are described. Dominant spontaneous vegetation types, such as steppes, meadows, prairies, savannas, and forests, and the characteristic species and communities are described in each phytogeographic province and vegetation unit. In addition, a brief comparison between the maps of the aeolian units and vegetation units is presented.