Astrophytum myriostigma

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.

Morphology

Astrophytum myriostigma is a spineless cactus defined by the presence of three to seven (usually five) pronounced vertical ribs which define the cactus' shape when young (the genus name "astrophytum", literally, "star plant", is derived from the resulting star-like shape). As the cactus ages, more ribs may be added and it becomes more cylindrical in shape, growing up to about 70–100 cm (2 ft 4 in – 3 ft 3 in) tall and 10–20 cm (4–8 in) in diameter. In the wild, globose to cylindrical stem is covered with a whitish flocking of trichomes. Some horticultural varieties lack the flocking.