Greek stenos—narrow, referring to the mostly narrow cylindrical habit.
Habit tree-like to shrubby, rarely creeping; in nature sometimes forming dense thickets. Stems thick, strongly ribbed. Areoles generally well spaced. Spines numerous. Flowers diurnal or nocturnal, funnel- or bell-shaped. Pericarpel with areoles and small spines; flower tube with scales that are hairless in the axils. Fruit ovoid to spherical, fleshy, often spiny at first.
S. marginatus (DC.) A. Berger & Buxb., sometimes placed in this genus is now generally included with Pachycereus as P. marginatus (DC.) Britton & Rose. The two other commonly cultivated species are keyed out in the key.
Stems not clearly constricted; flower mouth broad.
About 25 species from tropical Americas.
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.
