Subspecies, varieties, forms and cultivars of plants belonging to the Sclerocactus uncinatus group

• Sclerocactus uncinatus (Galeotti) N.P.Taylor: subsp. uncinatus has usually only a single hooked central spine that points obliquely outward and 7-8 radials; Distribution: Mexico (Mostly around San Luis Potosí).
• Sclerocactus uncinatus subs. crassihamatus (F.A.C.Weber) N.P.Taylor: has 5 central spines and about 8 radials, the lowermost ones hooked. Distribution: Queretaro, Mexico.
• Sclerocactus uncinatus subs. crassihamatus var. mathssonii (Berge ex K.Schum.) nov. comb. ined.: has shorter but stronger spines. Distibution: Southern part of the areal, Guanajuato, Mexico.
• Sclerocactus uncinatus subs. wrightii (Engelm.) N.P.Taylor: has a long central spine that points upward and 8-10 radials. Distribution: Northern part of the areal, United States and northern Mexico.
• Sclerocactus uncinatus subs. wrightii f. cristatus hort.: Crested form.