BISHOP'S CAP CACTUS

(Astrophytum, or Echinocactus, myriostigma), species of cactus, family Cactaceae, native to central Mexico, with four or five distinct ribs that increase to eight or more with age. Spineless and globose, becoming cylindroid with age, it is covered with white flecks caused by scales. All four species of Astrophytum, which is sometimes regarded as a subgenus of Echinocactus, are cultivated as potted plants, their yellow flowers appearing on summer days. Fairly large, they are fragrant in at least some species or varieties.