Origin and Habitat: This taxon is relatively common in rocky areas and exposed parts in the higher parts of the Sierra de la Ventana, Buenos Aires, Argentina.

• Gymnocalycium platense var. ventanicola (Speg.) R.Kiesling
• Echinocactus gibbosus var. ventanicola Speg.

• 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: This subspecies differs from the type species by a larger number of spines: 9-14 radial spines arranged in 3-6 pairs, occasionally with an additional poorly developed pair in the upper part of the areola. Central spines 1-5, straight, weakly developed in young specimens, about 2.5 cm long on mature plants. However the distinguishing characteristics of Gymnocalycium platenseSN|8057]]SN|21427]] var. ventanicola, appear to fall within the natural variation of Gymnocalycium platenseSN|21427]]SN|21427]] and most authors have dismissed ventanicola as perhaps not worthy of even varietal status, but it still has a value for a collector because they identify plants with particular characters.
Similar species: It is close to Gymnocalycium gibbosumSN|21427]]SN|8057]] (DC) Pfeiff which is distinguished by its olive green or slightly purple spherical stem, thinner spines, and rather large flowers with smaller receptacles.

Bibliography: Major references and further lectures
1) Till H., Armerhauser H., Till W. “Neourdnung der Gattung Gymnocalycium – Teil II.” Gymnocalycium 21 (Sonderheft). P 815-838 (2008)

Cultivation and Propagation: Gymnocalycium platenseSN|21427]]SN|21427]] var. ventanicola 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).