Selenicereus, sometimes known as moonlight cactus, is a genus of epiphytic, lithophytic, and terrestrial cacti, found in Mexico, Central America, the Caribbean and northern South America. The term night-blooming cereus is also sometimes used, but this is also used for many night-blooming cacti, including Epiphyllum and Peniocereus. In 2017, the genus Hylocereus was brought into synonymy with Selenicereus. A number of species of Selenicereus produce fruit that is eaten. The fruit, known as pitaya or pitahaya in Spanish or as dragon fruit, may be collected from the wild or the plants may be cultivated.

A pitaya or pitahaya is the fruit of several different cactus species indigenous to the region of southern Mexico and along the Pacific coasts of Guatemala, Costa Rica, and El Salvador. Pitaya is cultivated in East Asia, South Asia, Southeast Asia, the United States, the Caribbean, Australia, Brazil, and throughout tropical and subtropical regions of the world.