Cereus chalybaeus is a cactus from the genus Cereus, a genus consisting of about 25 species of tree-like cacti. Cereus chalybaeus is a columnar cactus with 5-6 ribbs. It is few-branched and often purple tinged. It has spines that at first are red, but with age turn black. In summer it bears funnel-shaped flowers, which can be up to 8 inches long. The inner petals are white and the outer petals are either purple or red. Cereus chalybaeus can grow up to 10 feet tall and can be up to 28 inches in diameter. This plant is native in hardiness zones 13-15 (Northern Argentina and Uruguay).