Origin and Habitat: Echinocereus polyacanthusSN|7070]]SN|7070]] is widely distributed, locally common across Southern USA (South-eastern Arizona, Western New Mexico), large areas in northwestern Mexico (Chihuaua, Durango, Cosihuiriachi, It also occurs in the Sierra Madre Occidental in eastern Sonora and into the Baja California Peninsula)
Altitude: 1300 and 2000 metres above sea level.
Type Locality: Mexico, Chihuahua, Cosihuiriachi.
Habitat and Ecology: It grows on rocky outcrops in oak and pine woodlands. Blum et al. (1998) reported it from rocky mountain slopes in volcanic or sedimentary rocks with humus pockets. This species is common and abundant across its range and there are not major threats to this species.

• Echinocereus polyacanthus Engelm. in Wisliz.
• Echinocereus triglochidiatus subs. polyacanthus (Engelm.) U.Guzmán
• Echinocereus triglochidiatus var. polyacanthus (Engelm.) L.D.Benson

• Echinocereus polyacanthus Engelm. in Wisliz.
• Echinocereus triglochidiatus subs. polyacanthus (Engelm.) U.Guzmán
• Echinocereus triglochidiatus var. polyacanthus (Engelm.) L.D.Benson
• Echinocereus leeanus (Hook.) Lem.
• Cereus leeanus Hook.
• Echinocereus leanus
• Echinocereus matthesianus Backeb.
• Echinocereus multicostatus (Cels) Cels ex Rümpler
• Cereus multicostatus Cels
• Echinocereus leanus var. multicostatus (Cels) K.Schum.
• Echinocereus triglochidiatus var. multicostatus (Cels) W.T.Marshall
• Echinocereus santaritensis W.Blum & Rutow in W.Blum et al.

• Echinocereus polyacanthus subs. acifer (Otto ex Salm-Dyck) N.P.Taylor
• Cereus acifer Otto ex Salm-Dyck
• Echinocereus acifer (Otto ex Salm-Dyck) F.Haage
• Echinocereus triglochidiatus var. acifer (Salm-Dyck) Bravo
• Echinocereus acifer subs. tubiflorus W.Rischer in W.Blum et al.
• Echinocereus marksianus Fritz Schwarz in Backeb.
• Echinocereus polyacanthus var. densus (Regel) N.P.Taylor
• Echinocereus polyacanthus var. densa ( Regel ) N.P.Taylor (Regel) N.P.Taylor
• Echinopsis valida var. densa Regel

• Echinocereus polyacanthus subs. huitcholensis (F.A.C.Weber) N.P.Taylor
• Cereus huitcholensis F.A.C.Weber
• Echinocereus acifer subs. huitcholensis (F.A.C.Weber) Mich.Lange
• Echinocereus huitcholensis (F.A.C.Weber) Gürke
• Echinocereus polyacanthus var. huitcholensis (F.A.C.Weber) N.P.Taylor
• Echinocereus triglochidiatus subs. huitcholensis (F.A.C.Weber) U.Guzmán
• Echinocereus plomosus hort.

• Echinocereus polyacanthus subs. pacificus (Engelm. ex Orcutt) Breckw.
• Cereus pacificus (Engelm.) J.M.Coult.
• Cereus phoeniceus var. pacificus Engelm. ex Orcutt
• Echinocereus pacificus (Engelm. ex Orcutt) Britton & Rose
• Echinocereus polyacanthus var. pacificus (Engelm. ex Orcutt) N.P.Taylor
• Echinocereus triglochidiatus subs. pacificus (Engelm. ex Orcutt) U.Guzmán
• Echinocereus triglochidiatus var. pacificus (Engelm. ex Orcutt) Bravo
• Echinocereus triglochidiatus var. pacificus (Engelm. ex Orcutt) W.T.Marshall
• Echinocereus mombergerianus G.Frank
• Echinocereus pacificus subs. mombergerianus (G.Frank) W.Blum, W.Rischer & Rutow in W.Blum et al.
• Echinocereus polyacanthus subs. mombergerianus (G.Frank) Breckw.

Description: Echinocereus polyacanthusSN|7070]]SN|7070]] is low growing, solitary or clumping cactus, forming large cushions, generally less than 50, but occasionally of several hundred stems. This species is very variable, and the several varieties are so different-looking that the only uniting factor is the bright red bloom and rounded petals.
Stems: Light green, often tinged with red, cylindrical tapering toward the tip, each stem up to 30 cm tall, 7 cm in diameter.
Ribs: 9 to 13, usually 10 well defined ones, low, either tuberculate or not.
Areoles: Approximately 1-1.5 cm apart, and somewhat woolly.
Central spines: 1 to 7, yellowish or brown, expanded basally, straight, elongated, becoming grey as they age, reaching up to 5 cm long, but variable in length.
Radial spines: 6 to 17 (usually about 12), dirty white or reddish, often overlapping, up to 2 cm long but often much shorter.
Flowers: Diurnal, arising near the stem's apex, tubular to funnel-form, brilliant pinkish-orange to deep red with a yellowish or whitish colored throat, 3-14 cm long, 3-8 cm in diameter, ovary and tube with yellowish spines and abundant cobwebby wool in the axil of the scales, which is lacking in other similar species.
Blooming season: Apr-Jun, the flowers remain open for 2 or 3 days. Blooming generally begins 5 to 10 years after sowing, as the plant matures.
Fruits: Ovoid, green, with white pulp, indehisent and edible.
Remarks: Originally this species was incleded in Echinocereus triglochidiatusSN|7140]]SN|10576]], a name used for a large group of diploid and polyploid taxa treated as conspecific by L. D. Benson (1969, 1982). The tetraploids are now recognized distinct species such as Echinocereus coccineusSN|10576]]SN|7140]], including Echinocereus polyacanthusSN|7070]]SN|7070]] Engelmann of Mexico.

Bibliography: Major references and further lectures
1)James Cullen, Sabina G. Knees, H. Suzanne Cubey "The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass" Cambridge University Press, 11/Aug/2011
2) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
3) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
4) Baker, M. & Van Devender, T. 2013. Echinocereus polyacanthus. In: IUCN 2013. "IUCN Red List of Threatened Species." Version 2013.2. <www.iucnredlist.org>. Downloaded on 14 January 2014.

Cultivation and Propagation: This cactus is widely cultivated for its flowers. It is among the easiest species to grow, flower and propagate. Water regularly from March to October. Rot prone in winter, it needs good drainage. Claret Cups require strong sunlight to maintain a healthy appearance, and a harsh "dry and cool" winter environment combined with maximum light exposure enhances spring flower production.
Frost Tolerance: Depends on the variety. The species from Baja California is less resistant (hardy to -5° C); the other varieties are much more cold resistant (some populations can tolerate temperatures down to -12° C or less)