Queen of the Night is a night-blooming, tropical epiphyte to lithophyte with huge showy fragrant white flowers that close up by dawn. There are no true leaves, but flattened stems that can be easily rooted.
Give this plant well-drained average succulent/cactus soil mix in partial shade or bright, indirect light. Soak the soil completely when watering and water frequently, letting the top of the soil dry out between waterings. Bring inside when temperatures cool and cut down on watering during the winter to 1-2 times per month.
Last two photos show mature plant in bloom - what you can expect with proper care :)
Also known as Dutchman's Pipe Cactus, Lady of the Night, Night-blooming Cereus.
Light: Bright indirect light
Water: Sparingly, only when soil has completely dried out. Less in winter.