Origin and Habitat: Argentina (Córdoba and Buenos Aires Province). The original specimens was collected in Prov. Buenos Aires, Ventana, Valle de las Vertientes in 1895 by Spegazzini.
Altitude range: 300-700 metres above sea level.
Habitat and ecology: This plant comes from the arid hills of Pampas (Sierra de la Ventana, Curámalál, Olavarria etc.) mainly in the cracks of the rocks.

• Gymnocalycium platense (Speg.) Britton & Rose
• Echinocactus gibbosus var. platensis (Speg.) Speg.
• Echinocactus platensis Speg.
• Gymnocalycium gibbosum var. ventanicola (Speg.) Y.Itô
• Gymnocalycium reductum var. platense (Speg.) R.Kiesling

• Gymnocalycium platense (Speg.) Britton & Rose
• Echinocactus gibbosus var. platensis (Speg.) Speg.
• Echinocactus platensis Speg.
• Gymnocalycium gibbosum var. ventanicola (Speg.) Y.Itô
• Gymnocalycium reductum var. platense (Speg.) R.Kiesling
• Gymnocalycium platense var. ventanicola (Speg.) R.Kiesling
• Echinocactus gibbosus var. ventanicola Speg.
• Gymnocalycium stenocarpum (K.Schum.)
• Echinocactus stenocarpus K.Schum.

Description: Gymnocalycium platense is a small, usually unbranched, cactus species, depressed, half-hidden in the earth. It will flower when 3-5 cm in diameter. The flowers with long floral tube, open wide in sunlight, and are commonly white with a reddish reddish throat and a hint of dark shading at the tips of the tepals. This is a delightful plant and well worth growing.
Stem: Solitary, flattened globose to globose, green, dull bluish green, olive green, or purple or bronzed never greyish (rather variable in colour in cultivation depending on growing conditions), 8-10 cm high, 4-10 cm in width.
Ribs: 8-18, usually 13, broad and low, with strong cross-furrows, with distinct rounded tubercles. Tubercles with a horizontal or ascending chin-like projection.
Areoles: Deep-set, when young white-felted.
Radial spines: 3 to 7, thin, needle-like, subulate, rigid, more or less flattened against the stem surface, base swollen pale brown-red, greyish-purple, grey or blackish, with whitish tips, 5-15 mm long.
Central spines: Usually absent.
Flowers: Several together on the crown, diurnal, scentless, 3 to 6.5 cm in length and 4-6.5 cm across, openong wide in sunlight. Tube and ovary dull bluish green bearing a few broad, short, rounded scales, these more or less purplish on the edge. Outer perianth-segments white with a broad green or pinkish stripe down the center. Inner perianth segments pure white with a hint of dark shading at the tips of the tepals. Throat broad, white, reddish or purple within. Filaments numerous, scattered over the throat. Style short and thick, 2 cm long, stigma-lobes cream-coloured. Ovary oblong.
Blooming season: This plant blooms in early summer when it is only 3-4 cm.
Fruits: The ripened ovary is pink, almost spherical, 1-2.5 cm long, 1-2 cm in width, and dehisces (splits) down its length.
Seeds: 1.2-1.2 mm, matt black.
Remarks: Gymnocalycium platense is often confused commercially with unrelated species of the Gymnocalycium bodenbenderianumSN|14405]]SN|14405]] group and Gymnocalycium leptacanthum. Plants sold under this name but having flowers with red throat and glossy brown seeds are probably Gymnocalycium quelianum or a related species.

Notes: This species is strictly relate with Gymnocalycium stellatumSN|16383]]SN|11493]] and Gymnocalycium baldianumSN|11968]]SN|11968]] and it is very similar (if not the same) to Gymnocalycium quehlianumSN|11493]]SN|16383]].

Bibliography: Major references and further lectures
1) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
2) 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
3) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
4) N. L. Britton, J. N. Rose “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Volume 4, The Carnegie Institution of Washington, Washington 1923
5) Curt Backeberg “Die Cactaceae: Handbuch der Kakteenkunde” Gustav Fischer Verlag, Stuttgart New York 1982–1985

Cultivation and Propagation: Gymnocalycium platenseSN|21427]]SN|21427]] is very easy to grow, these plants offer no cultivation difficulties.
Watering Needs: Moderate to copious in summer, keep dry in winter.
Frost Tolerance: Quite frost resistant if kept dry -10° C (Temperature Zone: USDA 8-10 )
Cultural Practices: Feed with a high potassium fertilizer in summer.
Sun Exposure: Full sun to light shade
Propagation: Seeds (seldom produces offsets)