Giant Club Cactus

Tall bluish cactus with large pale yellow/green flowers. "With an often tree-like appearance, the Peruvian Apple Cactus' cylindrical gray-green to blue stems can reach 10 metres (33 ft) in height and 10-20 cm in diameter. The nocturnal flowers remain open for only one night. The fruits, known locally as "pitaya" or Peruvian Apple, are thornless and vary in skin colour from violet-red to yellow. The edible flesh is white and contains small, edible, crunchy seeds. The flesh sweetens as the fruit opens out fully." - Wikipedia