[1] Leucostele undulosa has a columnar growth habit, achieving a height of up to 2.5 meters (8 ft 2 in) and a trunk diameter of 11 centimeters (4.3 in).

Its dark green branches, measuring 15 centimeters in diameter, feature stems with 20 ribs and obovate gray areoles, each 2 mm (0.079 in) high and 8 mm (0.31 in) in diameter.

Within these areoles, 3-4 central spines, measuring 4 cm (1.6 in) in length, exhibit a white hue with brown markings, accompanied by 12 radial spines measuring 1 cm (0.39 in) in length, displaying a spectrum from dark green to white with brown spots.

[2] Indigenous to Coquimbo, Chile, this species is found at altitudes of 400 meters (1,300 ft), specifically in low scrub areas and on rocks alongside Puya species.

[2] The nomenclature of this species is based on the undulating shape of its ribs, producing a tuberculate appearance.