Origin and Habitat: Oklahoma, USA.

• Echinocereus oklahomensis Lahman

• Echinocereus reichenbachii (Terscheck ex Walp.) Haage jr. ex Britton & Rose
• Cereus reichenbachianus Labour.
• Echinocactus reichenbachianus (Terscheck) Terscheck ex Fennel
• Echinocactus reichenbachii Terscheck ex Walp.
• Echinocereus caespitosus var. reichenbachii (Terscheck ex Walp.) Borg
• Echinocereus pectinatus var. reichenbachii (Terscheck ex Walp.) Werderm.
• Echinocereus reichenbachianus hort. ex Haage
• Echinopsis pectinata var. reichenbachiana (Terscheck) Salm-Dyck
• Echinopsis reichenbachiana Pfeiff. ex C.F.Först.
• Echinocereus caespitosus var. castaneus (Engelm.) Rümpler in Förster
• Cereus caespitosus var. castaneus Engelm. in A.Gray
• Cereus reichenbachianus var. castaneus Labour.
• Echinocereus caespitosus var. major (Engelm.) Rümpler in C.F.Först.
• Cereus caespitosus var. major Engelm.
• Echinocereus caespitosus var. minor (Engelm.)
• Cereus caespitosus var. minor Engelm.
• Echinocereus pailianus
• Echinocereus reichenbachii f. albispinus hort. non Lahman
• Echinocereus reichenbachii var. anigosanthus Y.Itô
• Echinocereus reichenbachii f. brevispinum hort.
• Echinocereus reichenbachii subs. burrensis G.Frank, Metorn & E.Scherer
• Echinocereus reichenbachii subs. caespitosus (Engelm.) W.Blum & Mich.Lange in W.Blum et al.
• Cereus caespitosus Engelm. & A.Gray
• Echinocereus caespitosus (Engelm.) Engelm. in Wisliz.
• Echinocereus pectinatus var. caespitosus (Engelm.) K.Schum.
• Echinocereus pectinatus f. caespitosus (Engelm.) Schelle
• Mammillaria caespitosa (Engelm.) A.Gray
• Echinocereus reichenbachii var. castaneus (Engelm.) nov. comb. ined.
• Echinocereus caespitosus f. castaneus (Engelm.) Borg
• Echinocereus castaneus (Engelm.) Orcutt
• Echinocereus reichenbachii subs. comanchensis D.Felix, Oldach & J.Oldach
• Echinocereus reichenbachii f. cristatus hort.
• Echinocereus reichenbachii var. purpureus (Lahman) D.Parker
• Echinocereus caespitosus var. purpureus (Lahman) D.Weniger
• Echinocereus purpureus Lahman
• Echinocereus rotatus Linke
• Echinocereus pectinatus var. rotatus (Linke) Linke ex Haage
• Echinocereus texensis Jacobi

• Echinocereus reichenbachii var. albertii L.D.Benson
• Echinocereus fitchii subs. albertii (L.D.Benson) W.Blum & Mich.Lange in W.Blum et al.

• Echinocereus reichenbachii subs. armatus (Poselg. ex Engelm.) N.P.Taylor
• Cereus pectinatus var. armatus Poselg. ex Engelm.
• Echinocereus armatus (Poselg.) A.Berger
• Echinocereus caespitosus var. armatus (Poselg. ex Engelm.) Borg
• Echinocereus fitchii var. armatus
• Echinocereus reichenbachii var. armatus (Poselg. ex Engelm.) N.P.Taylor
• Echinocereus spinosus (J.M.Coult.) Borg
• Cereus pectinatus var. spinosus J.M.Coult.

• Echinocereus reichenbachii subs. baileyi (Rose) N.P.Taylor
• Echinocereus baileyi Rose
• Echinocereus reichenbachii var. baileyi (Rose) N.P.Taylor
• Echinocereus baileyi var. brunispinus Backeb.
• Echinocereus baileyi var. caespiticus Backeb.
• Echinocereus longispinus Lahman
• Echinocereus mariae Backeb.
• Echinocereus oklahomensis Lahman
• Echinocereus reichenbachii var. albispinus (Lahman) L.D.Benson
• Echinocereus albispinus Lahman
• Echinocereus baileyi var. albispinus (Lahman) Backeb.
• Echinocereus longispinus var. albispinus Backeb.
• Echinocereus reichenbachii var. baileyi f. albispinus

• Echinocereus reichenbachii subs. fitchii (Britton & Rose) N.P.Taylor
• Echinocereus fitchii Britton & Rose
• Echinocereus reichenbachii var. fitchii (Britton & Rose) L.D.Benson
• Echinocereus melanocentrus J. Lowry

• Echinocereus reichenbachii subs. perbellus (Britton & Rose) N.P.Taylor
• Echinocereus perbellus Britton & Rose
• Echinocereus reichenbachii var. perbellus (Britton & Rose) L.D.Benson

Description: Echinocereus oklahomensisSN|7575]]SN|21800]] true to its name, is found in south-west Oklahoma. It is one of the morphological or local forms of the very variable Echinocereus reichenbachiiSN|21800]]SN|7575]] subs. baileyi distinguished by having 20-24 radial spines only 2 cm long and 0-2 centrals. There are no other clear distinguishing features, and they must all be regarded as the same species.
Habit: Solitary or branching from the base.
Stems: Cylindrical 10-20(40) cm tall 4-10 cm in diameter.
Ribs: About 15 acute, slender or sometimes arranged spirally, bearing oval areoles.
Central spines: No central spine (usually) or occasionally 1 or 2.
Radial spines: 20-24 needle-shaped, bristly spreading which point outward and downward, white, yellow, reddish, brownish or pinkish, about 2 cm long cm long.
Flowers: Funnelform magenta-pink close to the end of the stems of the youngest areoles, which are white and woolly. 6-12 cm in diameter. Stamen yellow; stigma green; style white. They have a spiny, woolly, funnel-shaped tube.

Bibliography: Major references and further lectures
1) Edward F. Anderson (2001) “ The Cactus Family”.
2) Curt Backeberg “Cactus Lexicon” Sterling Publishing Company, Incorporated, 1978
3) David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006
4) Del Weniger “Cacti of the Southwest: Texas, New Mexico, Oklahoma, Arkansas, and Louisiana” University of Texas Press, 1969
5) 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 GlassCambridge University Press, 11/ago/2011
6) Lyman David Benson “The Cacti of the United States and Canada” Stanford University Press, 1982

Cultivation and Propagation: Echinocereus oklahomensisSN|21800]]SN|21800]] is fairly easy to grow. It makes great potted specimens.
Soil: Use a mineral well permeable soil with little organic matter (peat, humus). It grows in limestone areas of Texas (Big Bend area) and adjacent areas of Mexico, so will probably benefit from extra calcium in its soil.
Growth rate: It grows well, though slowly, but it possible to increase the speed of growth to some extent by providing adequate amount of water, warmth, and a liquid fertilizer diluted half strength during the active growing season, but it’s susceptible to rotting if too wet. Most plants will offset readily, and clumps can be produced in a few years.
Soil: It needs a very porous, slightly acidic potting medium (add pumice, vulcanite, and perlite). Outdoors it does well on poor, rocky soils.
Exposure: It likes a sunny position also blasting sun in summer. If grown indoor provide 4 to 6 hours, or more, direct morning or afternoon sun.
Watering: It is sensitive to overwatering (rot prone) needs a very good drainage to avoid rotting, but requires more moisture than true desert cacti to grow and produce flowers.
Hardiness: It its natural environment it is very cold resistant from -10° to -25° C (depending on clones) or less for short periods of time. It can be grown outdoors in Mediterranean warm-temperate climates, But for safe cultivations needs anyway to kept above 5 °C and dry in winter. But it can tolerate temperatures down to -5° C (or even less) for very short periods if very dry and ventilated. During winter month, put them in a cool luminous place and encourage them to enter winter dormancy by withholding water and fertiliser over the winter as they will etiolate, or become thin, due to lower levels of light.
Maintenance: Repot every two years. Needs lots and lots of space to grow, use large shallow container or bowl filled with very porous compost. It like pots with generous drain holes.
Pest & diseases: They are susceptible to fungal diseases if overwatered, but are not nearly as sensitive as many other cacti, especially in warm weather. If kept damp through cold periods, they will invariably suffer.
Uses: It is a fine plant for a rock garden or container, contrasts well with agaves, yuccas, and low-growing flowering plants.
Propagation: Seeds, also can be grown from cutting as it slowly branches from the base. The seeds may be germinated and grown in containers. Their main requirements consist of high humidity levels, free-draining soil mix, and enough water, light, and nutrition.