2" x 2", (seed propagated). One of the most cold hardy South American species, this small barrel-type plant forms clusters of low, thick growing stems covered with white spines. The large flowers are an unusual shade of lavender-white. Zones 6-10. *GYMNOCALYCIUM:* This huge genus of South American cacti has some cold hardy species found in the mountains of southern Argentina. Notable for their stout spines and white (rarely pink) oversized flowers, this genus is rarely encountered in North American gardens.