Cereus

Cereus, genus of plants of the cactus family, including a large but undetermined number of species. The genus is found in the southern United States, Mexico, South America, and the West Indies. Many species are common in cultivation, some of them under the name of night-blooming cereus. The best-known species in the United States is the saguaro, or giant cactus, which commonly occurs in Arizona and adjacent Sonora State, Mexico. This plant grows to 15 m (50 ft) high. Young plants consist of a single trunk, but older plants may have 20 or more upturned branches. The night-blooming cereus of the desert is well known for its very large white, fragrant flowers, nearly all of which bloom at night. In several different recent classifications, the genus has been divided into as many as ten genera.

Scientific classification: The genus Cereus belongs to the family Cactaceae. The saguaro, or giant cactus, is classified as Cereus giganteus. The night-blooming cereus of the desert is classified as Cereus greggii.