Body solitary or in clusters, to about 35 cm tall and 15 cm wide. Ribs 8-13. Tubercles with areoles often having a furrow and nectary. Central spines 0-5 to about 3 cm long. Radial spines 8-17, mostly to 3 cm long. Flower 4-8 cm wide, mostly magenta but pale in throat. Fruit brownish, scaly, eventually dry and opening by a basal pore.

N & NE Mexico, North America (S Texas)

There are 3 varieties, the two keyed out being the most readily available.

Source: Thompson, A, ; Forbes, S.; Spencer, R. (1997). Cactaceae. In: Spencer, R.. 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.