A common pincushion cactus is a ball-shaped perennial that produces spiny tubercles. The plant also produces reddish-purple flowers that bloom up to 2 inches wide and later develop into brown fruits. The common pincushion cactus is closely related to the Missouri pincushion cactus, which produces greenish-yellow flowers and red fruit.
Both pincushion cactus varieties are referred to as ball cacti because of their shape. Both varieties appear as far north as Canada and as far south as Texas. These plants are visible only in the spring, when half of the plant appears above ground to bloom. The remaining half of the plant stays below ground during the blooming season, and the top half sinks back underground in late summer.