Mammillaria sempervivi belongs to Cactaceae (the Cactus family). It is an evergreen perennial herbacious plant that is distributed from central to northern Mexico. This cactus is flattened spherical to depressed spherical, cloudy gray-green and 7-10 cm in diameter. The axillae are woolly. The 2 to 3 central spines are strong, reddish brown to black, turn gray with age and 4 mm long. The 2 to 6 radial spines can usually only be observed in the new shoot. They are white, somewhat bristle-like and up to 3 mm long. The flowers are funnel-shaped, cloudy white to light yellow and measure 1 cm in diameter as well as in length. They have a pink streak in the middle of the petals.