Night-blooming cactus. Image 1 of 5. Close-up of the flower of a cactus (Cereus sp. ) beginning to open after nightfall. This cactus is indigenous to South America. The flowers have a sweet and pervasive fragrance which attracts the hawk moths which pollinate them. The flowers bloom for one night only. It is a large and hardy cactus, and a popular ornamental plant. (See B620/050-054 for flower opening and closing).