I present a paper dealing with the family Cactaceae in the Pampas, which were studied by field surveys (2001–2023) and analysis of relevant literature. For each genus, species richness in the study area, general distribution, detailed maps concerning the study area, and original pictures are provided. The species were assessed according to the IUCN categories and criteria. A key for the identification of the genera in study area was proposed. A description of the main found phytophysiognomies (field, saxicola, forest, and wetland), in which the cacti grow, were also given using the Walking Method. Around sixty-three Cactaceae taxa were registered covered, belonging to the following genera: Parodia taxa, including a nomenclatural change, i.e. P. ritteriana comb. nov. (≡ Notocactus ritterianus), two new species (Frailea erythracantha and Parodia hofackeriana), and Frailea, Gymnocalycium, Wigginsia, Echinopsis, Cereus, and Opuntia. The floristic diversity found in the study area is related to the edaphic and climatic conditions provided by the stony springs, which constitute a favorable microclimate of intense luminosity, heat and humidity for xerophytic species to develop in open areas.