(This plant comes in a 2.5 inch pot. You will receive a very similar plant to the one in the picture. It may or may not be blooming at the time of your purchase. The plant is shipped in its pot to prevent any damage to the roots).
Native to Brazil.
Sun exposure: Requires full sun to filtered sun.
Hardiness: keep above 4.5 °C (40 °F)
Bloom color: The flowers are bright yellow, rather large compared to the rest of the plant.
Hardiness: Hardy to 25°F. Full sun to light shade. Keep dry winter.
They have the ability to hide in the soil when not enough water around. Once sufficient moisture is available the plant swells and is again visible on the top of the soil.
Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz