Structure and identification
The stem is flattened or spherical, partly hidden in the soil and continuing into a tuberous root. Tubercles are broad, with a flat upper side positioned almost parallel to the ground. Lateral spines remain few and relatively short. A single stronger central spine appears in older plants. Flowers are white or yellowish white, sometimes with a pinkish stripe. The authors observed complete grooves late, despite earlier flowering. [Dicht and Lüthy 2005, pp. 63–65]
Habitat and variation
The monograph documents sites near the city of San Luis Potosí, on clay grasslands with erosion hollows. The authors describe red glands in well-hydrated plants and note that the condition of material transported into collections influenced earlier species recognition. [Dicht and Lüthy 2005, pp. 63–65]