bishop’s cap cactus, (Astrophytum myriostigma), species of spineless cactus (family Cactaceae) native to Texas and central Mexico. The plant is a common ornamental species.
Bishop’s cap cactus usually reaches no more than 100 cm (39 inches) in height and up to 20 cm (8 inches) in diameter. It has four or five distinct ribs that increase to eight or more with age. The plant is globose when young, becoming cylindroid as it gains more ribs. The gray-green flesh is covered with white flecks. The fragrant yellow flowers have numerous petals and usually appear in early spring or summer during the day.