Haageocereus decumbens is a species of Haageocereus found in S. Peru to Chile (Tarapacá) [1]
Haageocereus decumbens grows spread out or ascending and often forms richly branched groups with slender shoots that reach diameters of up to . There are about 20 low ribs. The one or two light to dark brown central spines are directed downwards and are up to long. The up to 30 and more needle-like yellowish radial spines have a length of .
The white flowers reach a diameter of and a length of up to .[2]
Haageocereus decumbens is distributed in Peru in the Arequipa region near Chala and Mollendo at altitudes of 200 to 700 meters.
The first description as Cereus decumbens was made in 1913 by Friedrich Karl Johann Vaupel.[3] Curt Backeberg placed the species in the genus Haageocereus in 1934. Other nomenclature synonyms are Borzicactus decumbens (Vaupel) Britton & Rose (1920), Binghamia decumbens (Vaupel) Werderm. (1937, incorrect name ICBN article 11.4) and Echinopsis decumbens (Vaupel) Mayta (2015).