This is a vintage botanical illustration of a cactus with a blooming flower. The cactus is tall and cylindrical, with a deep green hue. It's covered in numerous spines, which are depicted as small, dark points. A flower is shown in bloom, with white petals and a central cluster of yellow stamens. The flower is connected to the cactus by a green stem. Several smaller, pointed leaves are also visible around the flower and stem. The illustration is set against a pale, cream-colored background. At the bottom of the image, there's text identifying the plant, 'Cereus Perotianus'. The style is detailed and realistic, typical of botanical illustrations from the 19th or early 20th century.