Mexican pincushion cactus

Mammillaria magnimamma is a perennial globose plant reaching a height of 15–30 cm and a diameter of about 13 cm. At first it grows solitary, but later forms large clumps rising above ground level. Tubercules are four-sided, with latex and the axils have dense white wool. The radial spines are 2 - 5, quite variable and unequal, with dark tips, 15 – 45 mm long. Flowers are pink or white cream with reddish midveins and a diameter of 20 – 25 mm. They bloom in mid Spring. Fruits are club shaped, dark red, about 20 mm long, and contain little brown seeds.

This species is widespread throughout central Mexico, at an elevation of 100–2,700 metres (330–8,860 ft) above sea level. Its status is listed as "Least Concern" by the IUCN Red List.

Mammillaria magnimamma can tolerate temperatures down to 1 °C (34 °F), so in temperate zones may be placed outside during the summer months, but in winter requires protection from frost and inclement weather. It needs to be grown in a well-drained medium in full sun. It has gained the Royal Horticultural Society's Award of Garden Merit.