Stem segments erect, flattened, obovate, 7-22(-35) × 6.5-13.5(-16) cm; areoles (8-)10-16(-19) per diagonal row across midstem segment, circular. Spines absent or very rarely 1-few very short spines per stem segment. Fruits spineless. 2n = 22.

Flowering late winter-spring (Feb-Jun). Chaparral, woodlands, desert flats, hills, sandy to rocky soils; 300-1700 m; Ariz., Calif., Nev., Utah; n Mexico.

PADS: erect, obovate, flattened throughout, 7-22(-35) cm long, 6.5-13.5(-16) cm broad. AREOLES: (8-)10-16(-19) in a diagonal row across midpad, circular. SPINES: absent (or very rarely 1-few very short spines per pad). FRUITS: spineless. 2n = 22. NOTES: See also parent taxon. Sandy to rocky desert flats and hills to chaparral and woodlands, La Paz, Maricopa, Mohave, Yavapai, Yuma cos.; 350-1700 m (1200-5600 ft); Feb-Jun; AZ, se CA, UT; adjacent Mex. REFERENCES: Pinkava, Donald J. Cactaceae. 2003. J. Ariz. - Nev. Acad. Sci. Volume 35(2).