Greek skleros—hard, cruel, referring to the vicious spines.
Body mostly solitary, compressed spherical to cylindrical, generally spirally ribbed with spiny tubercles. Areoles often with nectar-secreting glands and extending beyond the spine source. Flowers at the body apex, funnel- to bell-shaped; summer. Pericarpel and flower tube naked with few to many scales without hairs in the axils. Fruit variously shaped, fleshy but becoming dry and with persistent flower remains, often scaly, and frequently opening by slits from the base. [Toumeya Britton & Rose, Echinomastus Britton & Rose, Ancistrocactus Britton & Rose and others]
Genus doubtfully distinct from Pediocactus Britton & Rose. Mostly cultivated as the single species S. uncinatus (Galeotti) N.P. Taylor from N Mexico and S North America which is destinguished by the lower 3 radial spines of each areole which are thick and curved or hooked; the typical plant is to about 8 cm wide, the lowermost central spine 5-11 cm long with flowers brownish red while var. crassihamatus (F.A.C. Weber) N.P. Taylor which is to 15 cm wide with the lowermost central spine to 5 cm long and perianth segments with white margins.
Stigmas green; spines often hooked and sometimes flattened and papery.
15-18 species from N Mexico and SW North America.
Source: (1997). Cactaceae. In: . Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.
