Gymnocalycium eurypleurum

Gymnocalycium eurypleurum grows singly with dull olive-green to brownish, flattened, spherical shoots that reach a diameter of 7 to 12 centimeters. The seven to twelve low ribs are slightly humpbacked. The one or two central spines, which are usually missing, are similar to the marginal spines. The four to seven penile, straight to slightly curved, brown marginal spines are 1 to 3 centimeters long. The white, pink flowers are up to 3 centimeters long. The whitish to purple-colored fruits are barrel-shaped and reach a diameter of up to 2 centimeters.

In the wild, the species is almost always solitary (non-clumping) and may grow in association with Frailea species. The species when grown in the greenhouse is also known for its fidelity to wild specimens. It is said to live in seasonally very dry habitat (annual rainfall 50–80 centimetres or 20–31 inches), clay soils between 6.8 and 7.2 pH, and maximum temperatures to 50 °C (122 °F). Gymnocalycium eurypleurum is an endemic species from Paraguay in the penumbra of the dry forests of the Alto Paraguay province at altitudes of 100 to 600 meters.