Stems eventually to just over 1 m tall and 4 cm wide and with 14-16 ribs. Areoles close-set with 13-22 spines to 3 cm long. Flowers red, s-shaped, stamens and style projecting.
C. icosagonus (Kunth) Rol.-Gos. from S Ecuador and N Peru, which also has flowers widening towards the tip, has much longer flowers (7-8 cm) with a more or less straight tube.
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.