A distinctive species with pale lilac woolly flowers that have perianth segments with fringed edges and a groove that does not extend all the way to the tubercle axis. Central spines 4-6, radial spines 9-15.
SW North America, Mexico
Generally grown as var. runyonii (Britton & Rose) L.D. Benson which is generally smaller than the species and with fewer spines.
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.