Several species of mamillarias are known as snowball cactus. These include the following.
Snowball cactus (Mamillaria bocasana)
This is also known as powderpuff cactus. Though it may start out as one small stem, it produces numerous offsets that eventually form a nice large clump.
When mature, this cluster can be nearly a foot in diameter with each body being about two inches across. The offsets arise near the base.
The globe-like plan is blue green, but much of the body is concealed by the long, flowing, silky hairs as well as the numerous, hooked yellowish to brown spines.
Very floriferous, this plant has small golden yellow or creamy white blossoms that open during the spring. These can have brownish-red tinges at the throat. These tend to be in a circle near the top of the plant from the joints of the tubercles. The blooms are less than ½ inch across. This is a very free flowering species.
Originally native to Mexico, this is one of the most commonly grown species. It is very easy to grow. This is propagated from shoots and offsets.
Snowball cactus (Mamillaria candida)
Native to Mexico, this occurs as a rounded greenish-blue, globe-like plant. It is slightly flattened at the top. This reaches three to over five inches in diameter. The many tubercles are crowded together. The plant has many crowded woolly white, bristle like spines as well as white spines.
The red blossoms open in clusters. They can also be pinkish with a hint of white along the edges of the petals. These flowers are small, only ½ inch in diameter.
Snowy pin cushion (Mamillaria celsiana)
This species is very similar to the snowball cactus. Native to Mexico, this looks similar to the snowball cactus. It is cylinder shaped at maturity. Snowy pin cushion can grow to over four inches tall and half as wide. Over time, it tends to produce clusters of offsets. This species is blue-green.
Snowy pin cushion is noted for its crowded tubercles that are arranged in very lovely patterns. Wooly white bristles arise from the axils of the tubercles. The spines range in color from white to yellow.
The rose blossoms tend to be rather small. They open in a circle around the apex of the plant during the spring. They’re only ¼ inch in diameter.