This is considered by some to be a subspecies of Mammillaria spinosissima, but these plants do not resemble each other in our experience. From an area of Guerrero, Mexico, Mammillaria pilcayensis has nearly felt like gray-yellow spines that nearly obscure a green body. This is a columnar type species with longish stems that may be upright or prostrate. The flowers are magenta to violet. These plants are seedlings in 4-inch pots.
