Mammillaria senilis is a species of cacti in the subtribe Cactinae. It is native to Mexico. The cactus grows in groups, and grow up to 8 inches tall. They form large red flowers that range from 5.5 to 6 centimeters in diameter.
Mammillaria senilis is a spiky, snowball of a cactus. This clustering species has distinctive, long white spines, some with hooked tips. Each globose stem can grow to 6.0" tall and 4.0" wide. With time they produce clusters of offsets. This cactus is native to Mexico and blooms with orange-red flowers perched on tall, narrow floral tubes.