Etymology -Named after the Mexican naturalist Romulo Numa Escobar.
The genus Escobaria includes species of small globose to cylindrical solitary or clumping stems with tubercles. Many of the species were once included in Coryphantha and earlier in Mammillaria. The inclusion in Mammillaria was largely due to overall habit of the plants and especially the presence of tubercles. Escobaria differs from Mammillaria in that it flowers from new growth at the top and lacks dimorphic areoles – that is the areoles do not have separate parts for producing spines and areoles. The distinction from Coryphantha is more subtle and is primarily in the seeds. The seeds of Escobaria are pitted (foveolate) unlike the crisscrossed (reticulate) seeds of Coryphantha. While the seeds are necessary to make a consistent distinction, other more generalized guidelines help differentiate Escobaria from Coryphantha. These other features include: a lack of extrafloral nectaries, fringed edges on the flowers, corking and falling off of tubercles with age and smaller, typically pink flowers.
Escobaria have a grooved tubercle and some otherwise similar plants have been moved out of Escobaria and into a separate genus Acharagma for lacking this groove.
Several species of Escobaria are quite popular in cultivation, but most notable are the species which are cold hardy. While many species are from warmer Mexico and the Southern United States, two species in particular range all the way north into Canada. It is these northern plains species that gardeners delight to grow in their cold-hardy gardens to break up the monotony of otherwise Opuntia-filled beds. There is also a species on the island of Cuba.