[2][3] Common species include the Missouri foxtail cactus P. missouriensis,[4] widespread in grassland and forest west of the Mississippi, and the spinystar P. vivipara,[5] distributed across the US and into Canada, first described by Nuttall in 1813.

Pelecyphores are spherical to club-shaped stem succulents up to 6 cm (2.4 in) in diameter and gray-green in color.

The areoles standing on the longitudinally or transversely flattened warts have thorns in a pectinate (comb-shaped) arrangement.

The flowers arise individually from short furrows on the upper surfaces of the youngest areoles.

The greenish fruits that form after the flowers are fertilized dry out when ripe and release the black seeds into the crown wool, from which they are only washed out (in nature) after a long time.