Mammillaria karwinskiana Mart.

Clustering by offsets or dichotomous branching, body globular, to 10 cm wide, with milky sap. Tubercles prominent, pyramidal. Axils woolly and bristly. Central spine 0(-1), to 25 mm. Radial spines 4-7, reddish, tips darker. Flowers white with maroon central stripe, 2 cm long, 1.5 cm wide. Fruit bright red.

S 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.