[3][4][5] Cereus are shrubby or treelike, often attaining great heights (C. hexagonus, C. lamprospermus, C. trigonodendron up to 15 metres or 49 feet).

The flowers are large, funnelform, 9–30 cm (3+1⁄2–11+3⁄4 in) long, usually white, sometimes pink, purple, rarely cream, yellow, greenish, and open at night.

[6] The name Cereus originates in a book by Tabernaemontanus published in 1625 and refers to the candle-like form of species C. hexagonus.

[10] Nathaniel Lord Britton and Joseph Nelson Rose (1919–1923) as well as Alwin Berger (1929) continued to divide Cereus into many genera.

[11] As of September 2023[update], Plants of the World Online accepted the following species:[1] Species that have formerly been accepted include: The range includes Brazil, northern Argentina, Paraguay, Uruguay, and Bolivia; more rarely it can be found in Peru, Colombia, Guyana, Suriname, and Venezuela.