Stems mostly clustering, more or less spherical, dark green to blackish or brown, arising from a tuberous root. Ribs 8-14. Areoles with 0-4 central spines and 7-13 radial spines. Flowers 3-4 cm long.
C. tenuissima F. F. Ritter is an invalid name for a similar but smaller plant with 13-16 ribs and flowers less than 3 cm long.
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.