This little-known genus of cacti consists of just two species, the other being the more commonly grown A. roseanum. The name means “not grooved” and was coined by Nigel Taylor as a subgenus within Escobaria. He recognized their distinctness from the rest of the species of that genus that possess grooved tubercles. Allan Zimmerman had previously suggested that these two species appeared “to be a separate genus”, a contention supported by subsequent DNA analysis which revealed a closer affinity to Lophophora and Obregonia than to Escobaria! A. aguirreanum has remained rarer in cultivation due to its water-sensitive nature. However, we offer what appears to be a more vigorous strain that is cultivated in Europe. The tuberculate bodies have a distinctive blue-green epidermis and mostly dark-brown spines, about 15 per areole, with little distinction between centrals and radials. The small flowers (under 2 cm or 3/4") seem to struggle out through the spines and are pale cream-colored, often with red midstripes on the backs of the outer tepals. The species is reported only from the west edge of the Sierra de la Paila in Coahuila, Mexico. HBG 123337, $8.