SPINES: lower central spine hooked, 2-6.3 cm long, 0.6-1 mm diameter, mostly white or straw; upper central spine 1.7-6.2 cm long, mostly 1 mm wide, mostly white or straw, rarely pink, mostly angled, rarely flat or rhombic in cross-section. FLOWERS: inner tepals rose or purple. NOTES: See also parent taxon. Along major river drainages in blackbrush communities: Coconino, Mohave, Navajo cos.; mostly at lower elevations, 1050-1500 m (3500-5000 ft); May-Jun; CO, UT. REFERENCES: Heil, Kenneth D., and Mark J. Porter. 2001. Cactaceae. J. Ariz. – Nev. Acad. Sci. Volume 33(1)