Greek stenos—narrow, referring to the extremely thin ribs.
Body solitary or clustering, low, more or less spherical to shortly cylindrical and with numerous thinly ridged ribs that are often wavy edged. Areoles mostly widely spaced. Spines of 2 kinds; large, generally flat central ones on upper side of areole and smaller radials below. Flowers small, funnel- or bell-shaped; mostly spring. Pericarpel with scales. Fruit mostly spherical, green, dry, scaly, splitting along one side.
Formerly known as Echinofossulocactus Lawr. and, like Ferocactus, this genus needs revision with several names misapplied or applied to different taxa, often under Echinocactus or Echinofossulocactus: S. dichroacanthus (K. Schum.) Pfeiff. is one of these. Within this genus there are many natural and cultivated hybrids and misuse of names making identification extremely difficult.
Ribs mostly thin and wavy-edged.
About 10 species from Mexico.
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.
