Mammillaria gigantea belongs to the Cactaceae (the Cactus family). It is a mammillaria (wart cactus) that is a native of Guanajuato, Queretaro and San Luis Potosi State in central Mexico. The plant body is blue-green, becomes 9-10 cm high and 15-17 cm in diameter with the close-set warts. It is dressed in white wool felt. The central spines are 4-6, robust, straight or more or less curved. The radial spines are up to 12, white and very small. The flowers are pale pink to greenish yellow and reach about 15 mm across. The fruits are pink to greenish.