Origin and Habitat: Argentina (San Luis)

• Gymnocalycium monvillei subs. achirasense (H.Till & Schatzl) H.Till
• Gymnocalycium achirasense H.Till & Schatzl
• Gymnocalycium horridispinum subs. achirasense (H.Till & Schatzl) G.J.Charles
• Gymnocalycium horridispinum var. achirasense (H.Till & Schatzl) Lodé

• Gymnocalycium monvillei (Lem.) Britton & Rose
• Echinocactus monvillei Lem.
• Gymnocalycium monvillei var. coloratum Neuhuber
• Gymnocalycium monvillei var. confusa Neuhuber
• Gymnocalycium monvillei subs. gertrudae (Neuhuber) Neuhuber
• Gymnocalycium monvillei var. gertrudae Neuhuber
• Gymnocalycium monvillei var. orientale Neuhuber
• Gymnocalycium achirasense var. orientale (Neuhuber) V.Gapon
• Gymnocalycium monvillei subs. achirasense var. orientale Neuhuber in H.Till & Neuhuber
• Gymnocalycium monvillei var. safronovii V.Gapon
• Gymnocalycium monvillei var. steineri H.Till
• Gymnocalycium multiflorum f. steineri.
• Gymnocalycium multiflorum (Hook.) Britton & Rose
• Echinocactus multiflorus Hook.
• Gymnocalycium multiflorum var. parisiense (K.Schum.) P.Fourn.
• Echinocactus multiflorus var. parisiensis K.Schum.
• Echinocactus multiflorus f. parisiensis (K.Schum.) Schelle
• Gymnocalycium polyanthum var. parisiense (K.Schum.) Y.Itô
• Gymnocalycium ourselianum (Cels ex Salm-Dyck) Y.Itô
• Echinocactus ourselianus Monv., Cels ex Salm-Dyck
• Gymnocalycium multiflorum var. ourselianum (Cels ex Salm-Dyck) H.Till & W.Till

• Gymnocalycium monvillei subs. achirasense (H.Till & Schatzl) H.Till
• Gymnocalycium achirasense H.Till & Schatzl
• Gymnocalycium horridispinum subs. achirasense (H.Till & Schatzl) G.J.Charles
• Gymnocalycium horridispinum var. achirasense (H.Till & Schatzl) Lodé
• Gymnocalycium monvillei var. chacrasense Neuhuber
• Gymnocalycium achirasense var. chacrasense (Neuhuber) V.Gapon
• Gymnocalycium monvillei subs. achirasense var. chacrasense
• Gymnocalycium monvillei var. echinatum Neuhuber
• Gymnocalycium achirasense subs. echinatum (Neuhuber) V.Gapon
• Gymnocalycium monvillei var. kainradliae Neuhuber
• Gymnocalycium achirasense subs. kainradliae (Neuhuber) V.Gapon
• Gymnocalycium monvillei f. villamercedense H.Till & Neuhuber
• Gymnocalycium achirasense var. villamercedense (H.Till & Neuhuber) V.Gapon
• Gymnocalycium villamercedense F.Ritter

• Gymnocalycium monvillei subs. brachyanthum (Gürke) H.Till
• Echinocactus brachyanthus Gürke
• Gymnocalycium brachyanthum (Gürke) Britton & Rose

• Gymnocalycium monvillei subs. horridispinum (G.Frank ex H.Till) H.Till
• Gymnocalycium horridispinum G.Frank ex H.Till

Description: It is a (usually) solitary geophytic cactus.
Stem: Flattened or globular, grey-green to olive green, 5-6 cm in diameter, up to 5 cm tall, but in cultivation it can become 7-8 cm high (or more) over the years.
Ribs: 12-15
Radial spines: Stout 10 up to 12, but usually less in young plants, bent against the body.
Central spines: Usually absent, or 1 erected one.
Flowers: Are some of the largest in this genus, often growing larger than the plant!, 6 up to 7 cm long and wide, dark to light purple, with a darker mid-strip.
Fruits: Green
Seeds: Dark brown.

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 Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006
3) Edward F. Anderson “The Cactus Family” Timber Press, 2001
4) E. W Putnam “Gymnocalyciums: Handbook No. 5.” National Cactus And Succulent Society, Smart & Co. (Printers) Ltd., Brackley, Northants. 1978
5) N.L. Britton, J.N. Rose. "The Cactaceae: Descriptions and illustrations of plants of the cactus family" Volume 3

Cultivation and Propagation: It is a summer grower species that offers no cultivation difficulties. Water regularly in summer (but do not overwater ) Keep this plant almost dry in winter at a minimum temperature of 0°C, prefer relatively rich substrate and low pH compost (if possible not limestone) otherwise growth will stop altogether. Feed with a high potassium fertilizer in summer. It is quite frost resistant if kept dry (hardy to -5° C)
Sun Exposure: Light shade. It may tolerate bright situations but is likely to suffer from sun scorch or stunted growth if over exposed to direct sunlight during the hottest part of the day in summer. This plant needs plenty of space for its roots, repotting should be done every other year or when the it has outgrown its pot. This species is particularly easy and accommodating, seldom suffer of cryptogamic diseases.
Propagation: Direct sow after last frost. (seldom produces offsets).Seed Collecting: Permit fruit to ripen. Fruit must be significantly overripe before harvesting seed; clean and dry seeds