The genus Laretia Gillies & Hook. comprises a single species, L. acaulis (Cav.) Gillies & Hook., of xerophilous subshrubs that form flat compact cushions. It is endemic to southern South America and is distributed through the high Andes of San Juan and Mendoza provinces in Argentina, and Atacama to Maule regions in Chile. Descriptions of Laretia are available only from the protologue and from a few regional floras; these are not comprehensive and are based on few specimens. Moreover, the actual geographic distribution of the genus has been questioned. In this work we present a taxonomic treatment for Laretia that includes field work, analysis of the protologue, and an exhaustive revision of herbarium material. We also analyze and describe the morphology and anatomy of its fruits because of their diagnostic importance in the family. We provide a detailed morphological description, ecological and ethnobotanical information, and illustrations of the genus. Additionally, we present a map that shows the geographical distribution of Laretia, designate lectotypes for three names, and finally analyze and resolve nomenclatural problems regarding two names (Laretia compacta and Laretia yareta) that have not been included in recent treatments and require revision in order to understand the limits of the genus.