Mammillaria capensis is a species of the genus Mammillaria in the cactus family(Cactaceae). The specific epithet capensis means, from the location in the Cape district at Puerto de Bahia '. Mammillaria capensis forms small groups. The cylindrical, olive-green plant body grows up to 25 centimeters high and up to 3 to 5 centimeters in diameter. The cylindrical warts are without milk juice . The axillae are occupied by 1 to 3 short bristles. The thorns are needle-like, reddish-brown to black with whitish base. The one central spine is stiff, usually hooked and 1.5 to 2 inches long. The 13 spines are 0.8 to 1.5 inches long The funnel-shaped flowers are pink to white. They grow up to 2 inches long and 2 inches in diameter. The cull red fruits contain black, grubige seeds .