Peniocereus is a genus of vining cacti, comprising about 18 species, found from the southwestern United States and Mexico. They have a large underground tuber, thin and inconspicuous stems.Its name comes from the prefix penio- (from the Latin penis, meaning ‘tail’) and Cereus, the large genus from which it was split. Known as the desert night-blooming cereus, it also shares its common names of “night-blooming cereus” and “queen of the night” with many other similar cacti.