Solitary, body elongate to 5 cm wide, 30 cm high, with milky sap. Tubercles conical, prominent. Axils woolly and bristly. Central and radial spines similar, in total 30, 5-6 mm long, whitish or yellowish, tips reddish or pale brown. Flowers reddish purple, 2 cm long and wide. Fruit pinkish-purple.

SW C Mexico

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. (as Mammillaria pilcayensis)