A syntaxonomic overview of shrubland vegetation in the southern Andean regions of Peru is presented. For each plant community, information is given on physiognomy, fl oristic diversity, ecology and geographical distri- bution. The shrub vegetation on the slopes of the upper Tambo river valley includes annual herbs, grasses, cacti and ferns. In total, 151 vascular species have been documented from forty-six relevés made at altitudes between 3470 and 3700 m. After classifi cation with TWINSPAN, one class, one order, one alliance, three associations, two subassocia- tions typicum and three subassociations, one variant, and two communities are distinguished. Hierarchically the class Echinopsio schoenii-Proustietea cuneifoliae comprises the order Echinopsio schoenii-Proustetalia cuneifoliae, and the alliance Salvion oppositiflorae, occurring in the Prepuna dwarf scrubs. Within the alliance the following 3 new associations (with subassociations) have been distinguished: Senecioni arnaldii-Exhalimolobetum weddellii (thorny rosette-like dwarf shrubs), Mostacillastro gracile-Chuquiragetum spinosae (high cover of shrubs) and Anredero diffusae-Diplostephietum meyenii (high cover of clustered columnar cacti and patches of thorny shrubs). Two communities have been distinguished: Opuntia rosea and Helogyne ferreyrae, and the community of Oph- ryosporus heptanthus and Escallonia myrtilloides, which includes several introduced species growing on heavily grazed wet slopes. The basal communities of Stipa ichu and Nassella asplundii have been also identifi ed. The most diverse families are Asteraceae, Poaceae and Cactaceae, followed by Solanaceae and Fabaceae. The vege- tation includes endemic, native and a few introduced species. DCA was used to interpret the correlation between environmental variables and species composition. Species composition is best explained by altitude, inclination and vegetation cover. © 2012 Gebrüder Borntraeger, 70176 Stuttgart, Germany.