Mammillaria duoformis T.T. Craig & E.Y. Dawson

Clustering, body elongate 3-4 cm wide. Tubercles prominent, conical. Axils with a few bristles. Central spines 4, 10-12 mm long, blackish-brown above, lower spine longer and hooked. Radial spines 18-20, 5-7 mm long, needle-like, tan at base, white or pale yellow above. Flowers crimson 15 mm long, 12 mm wide. Fruit pink.

SC 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.

kingdom Plantae
phylum   Tracheophyta
class    Magnoliopsida
superorder     Caryophyllanae
order      Caryophyllales
family       Cactaceae
genus        Mammillaria Haw.