Cereus peruvianus "Monstrosus," commonly known as the monstrose apple cactus, is a grey-blue cactus with a branching, treelike form. This slow-growing cactus even produces fruit similar to dragon fruit when mature.
Cereus peruvianus is a large, erect, thorny columnar cactus up to 9m (30 feet) tall when growing in the wild. Though less gigantic in pots, they are much admired for their sculptural, columnar shape, which contrasts impressively with that of most other plants in any collection of cacti. Cereus peruvianus is native from rocky outcrops and the savanna in South America. Cereus peruvianus flowers in summer and opens at night time. Each flower blooms only one night and then dies. The flowers are followed by red fruits 2.5-5cm (1-2 inch) in diameter.