Oreocereus is a genus of cacti (family Cactaceae), known only from high altitudes of the Andes.Its name means "mountain cereus", formed from the Greek prefix oreo- (ὀρεο-, mountain) and the New Latin cereus, meaning wax or torch. As they are covered with woolly white fuzz (modified spines), a few species in this genus are sometimes known as the old-man cactus, a generic name that also refers to Cephalocereus senilis or Espostoa lanata. More rarely, the old man of the mountain is also used for some species.