Denmoza is a monotypic genus in the cactus family (Cactaceae, order Caryophyllales), containing the single species Denmoza rhodacantha (synonym Echinopsis rhodacantha). It is native to northwestern and western Argentina, occurring on the eastern slopes and foothills of the Andes from the province of Mendoza north to Salta, at elevations between roughly 800 and 2800 meters.
Plants begin life as a globular cactus and remain in that form for an extended period before eventually developing into a column 0.5 to 1.5 m tall and 20 to 30 cm in diameter. The stem carries 30 or more tall, wide ribs. Young areoles are confluent and bear brownish-red spines that grey with age; each areole produces 8 to 10 slightly bent radial spines, and the flower-bearing areoles additionally produce long brown bristles and spines up to 7 cm long. The tubular flowers are scarlet, and the spherical fruits contain shiny black-brown seeds about 1.3 mm across.
The species has a long taxonomic history. Plants were probably first collected in 1821 by John Gilles near the city of Mendoza and given the (never validly published) name Cactus coccineus. It was formally described in 1834 as Echinocactus rhodacanthus by Joseph zu Salm-Reifferscheidt-Dyck. In 1922, Nathaniel Lord Britton and Joseph Nelson Rose established the genus Denmoza to accommodate the species, in their monograph The Cactaceae. Plants of the World Online continues to accept this placement.
Distribution
Denmoza rhodacantha, the genus's sole species, occurs on the eastern slopes and foothills of the Andes in northwestern and western Argentina, in provinces from Mendoza to Salta, at altitudes of 800 to 2800 meters.
Taxonomy Notes
Denmoza rhodacantha was likely first collected in 1821 near Mendoza, Argentina, initially described in 1834 as Echinocactus rhodacanthus, and transferred to the newly erected genus Denmoza by Britton & Rose in 1922 (authorship per GBIF). Plants of the World Online accepted this placement as of November 2025.
