This is a widespread and variable species, accounting for its more than a dozen synonyms. It occurs over a broad swath of dry tropical South America including Brazil, Uruguay and Argentina. The form offered here from Aigua, Dept. Maldonado, Uruguay, has flattened-globose stems to 6 cm (2.4") across, with 10 or more ribs. Its thin, flexible spines are appressed to the body forming a loose network with about a dozen yellowish radials and half that number of red-brown centrals. The flowers are the typically gorgeous, satiny yellow with contrasting red stigmas serving as a bullseye for bee pollinators. HBG 134691, $10.
Published in the Cactus and Succulent Journal, Vol. 91 (2), Summer 2019