Escobaria

Family Cactaceae. This genus has characteristics that help clarify the stages of evolution of modern cacti — the mamillarias. In the more primitive cacti the flowers are formed on the areole, directly above the cluster of spines.

For the mamillarias, at early stages of areole development it splits into two parts, producing a tubercle, or mamilla, and an axillary bud. Spines appear at the tip of the tubercle, and flowers or pups develop from the axillary bud. In Neobesseya, Escobaria and Coryphantha the axillary bud is large and conspicuous, and the tubercle has a groove. Escobaria are mainly found in Mexico and the adjacent southern states of the USA. Species that were previously grouped in the separate genus Neobesseya are now also assigned to this genus.

As a result of merging these genera, the northern boundary of the range, or the distribution area of the genus Escobaria, shifted to the northern states of the USA. And as a result of assigning the viviparous Coryphantha (Coryphantha vivipara) to the genus Escobaria — now called Escobaria vivipara (E. vivipara) — the northern boundary of the genus's range moved even further, since Escobaria vivipara can be found in southern Canada.

Usually Escobaria are covered with sharp bristles that protect the soft body of the plant. Cacti have a globular or pointed-at-the-top stem that produces numerous offsets, forming small cushion-like clumps. The flowers of these cacti are greenish-white, pale pink, pink or carmine-pink.

Plants of the subgenus Neobesseya are resistant to severe frosts, but the soil in which they grow must be absolutely dry. Other species of the genus require the same care as Coryphantha with densely arranged spines.