Astrophytum myriostigma, the bishop's cap cactus, bishop's hat or bishop's miter cactus, is a species of cactus native to the highlands of northeastern and central Mexico.
Synonyms include Echinocactus myriostigma, Astrophytum prismaticum, A. columnare, A. tulense, and A. nuda.
In botany, an infraspecific name is the scientific name for any taxon below the rank of species, i.e. an infraspecific taxon or infraspecies. The scientific names of botanical taxa are regulated by the International Code of Nomenclature for algae, fungi, and plants (ICN). As specified by the ICN, the name of an infraspecific taxon is a combination of the name of a species and an infraspecific epithet, separated by a connecting term that denotes the rank of the taxon. An example of an infraspecific name is Astrophytum myriostigma subvar. glabrum, the name of a subvariety of the species Astrophytum myriostigma (bishop's hat cactus). In the previous example, glabrum is the infraspecific epithet.
Names below the rank of species of animals and of cultivated plants are regulated by different codes of nomenclature and are formed somewhat differently.