Pfeiffer had published the first infrageneric division of Mammillaria in 1837, dividing the genus into two groups based on distinct spine characteristics. In 1845, Joseph zu Salm-Reifferscheidt-Dyck - based on work by Frederick Scheer - expanded the classification into eight groups. With at least 145 recognized species, it is one of the largest and most morphologically variable genera in the cactus family. Others estimate there are as many as two hundred species of Mammillaria, including sixty-two cultivated species from India. Though larger, the genus Opuntia is less popular with gardeners and landscapers. Mammillaria was previously thought to be monophyletic, but phylogenic analysis indicates that Mammilloydia is embedded within a 'core' group of Mammillaria species. A specimen of Mammillaria spinosissima was collected by Botanist David Hunt in September 1971, when he located one in Mexico, near the Morelos Cautla-Cuernavaca toll road in Sierra de Tepoztlan, at an altitude of .