Origin and Habitat: Northern Peru. This species has a very restricted range and occurs in only two isolated locations on the coast one near Malabrigo, now Playa Chicama, near the sea north of Trujillo, Region La Libertad, to km 720 in North Panamericana and the other one south of Trujillo.
Altitude range: Haageocereus pacalaensisSN|5657]]SN|5657]] is only present in coastal areas of La Libertad, at an altitude of 50 m to 250 metres above sea level.
Habitat and ecology: It occurs in coastal hills (lomas costeras). In Valle del Chicama (south of Trujillo), the Chavimochic irrigation project is severely threatening the survival of the subspecies Haageocereus pacalaensisSN|5657]]SN|5657]], as the area is being converted into agricultural fields. Already the project has resulted in the conversion of over 50% of the suitable habitat into agricultural fields, and this process is continuing. The other subspecies, Haageocereus pacalaensisSN|5657]]SN|5657]] subs. repens, which occurs north of Trujillo, is rare and threatened by expansion of the nearby urban area, hence it is considered Critically Endangered.

• Haageocereus pacalaensis Backeb.
• Binghamia pacalaensis (Backeb.) Werderm.
• Cereus pacalaensis

• Haageocereus pacalaensis Backeb.
• Binghamia pacalaensis (Backeb.) Werderm.
• Cereus pacalaensis
• Haageocereus horrens Rauh & Backeb. in Backeb.
• Haageocereus horrens var. sphaerocarpus Rauh & Backeb.
• Haageocereus laredensis Backeb. in Backeb. & F.M.Knuth
• Binghamia laredensis (Backeb.) Werderm.
• Cereus laredensis
• Cereus pseudomelanostele var. laredensis Backeb.
• Haageocereus pacalaensis var. laredensis (Backeb.) Krainz in Krainz
• Haageocereus pacalaensis var. longispinus (Rauh & Backeb.) Krainz in Krainz
• Haageocereus laredensis var. longispinus Rauh & Backeb.
• Haageocereus tenuispinus Rauh & Backeb. in Backeb.

• Haageocereus pacalaensis subs. repens (Rauh & Backeb.) Ostolaza
• Haageocereus pacalaensis var. repens (Rauh & Backeb.) Krainz
• Haageocereus repens Rauh & Backeb.

Description: Haageocereus pacalaensisSN|5576]]SN|5657]] is a srubby cactus species branching basally to produce several erect thick stems with a covering of dense golden spines. It is a somewhat variable taxon with several extreme forms that were early published as full species or as varieties, but these were too weak botanically to consider them as new species or subspecies, so they are all combined in Haageocereus pacalaensisSN|5657]]SN|5657]], except for the creeping subsp. repens.
Derivation of the specific name. “pacalaensis” For the occurrence near Pacala, Dept. Libertad, Peru. 
Stems: Columnar, branched from the base,1 to 1.7 m tall, 10-12 cm in diameter, yellowish green with close, yellow spines, flowers white.
Ribs: 17-20 low, 1 cm wide.
Areoles: Small, brownish felted.
Radial spines: up to 25(-40), fine, radiating, grey, to 10(-14) mm long yellow.
Central spines: 1-4, stout, grey, 1-7 cm long, pointing obliquely downwards, bright golden yellow.
Flowers: White, externally green, to 10 cm long.
Fruits: Globose, green to reddish green, to 8 cm in diameter.
Taxonomical notes: Calderón et al. (2007) indicate that H. pacalaensis is a synonym of Haageocereus pseudomelanosteleSN|5657]]SN|5576]]. However, Hunt et al. (2006) consider them as separate species. Taxonomic studies are needed to clarify this issue.

Bibliography: Major references and further lectures
1) Carlos Ostolaza Nano “Todos los cactus del Perú” December 2014
2) W. Rauh “Beitrag zur Kenntnis der peruanischen Kakteenvegetation” Springer-Verlag, 05 October 2013
3) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
4) Hunt, D., Taylor, N. and Charles, G. (compilers and editors). 2006. “The New Cactus Lexicon”. dh Books, Milborne Port, UK.
5) Arakaki, M., Ostolaza, C., Cáceres, F. and Roque, J. “Cactaceae endémicas del Perú.” Revista Peruana de Biología 13(2): 193s-291s. 2006.
6) Ostalaza, C., Cáceres, F. & Roque, J. 2013. Haageocereus pacalaensis. The IUCN Red List of Threatened Species 2013: e.T152353A627212. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T152353A627212.en. Downloaded on 14 December 2016.
7) Willy Cullmann, Erich Götz (Dozent Dr.), Gerhard Gröner “The encyclopedia of cacti” Timber Press, 1987
8) Urs Eggli, Leonard E. Newton “Etymological Dictionary of Succulent Plant Names” Springer Science & Business Media, 29 June 2013