Interesting cactus that is popular here in California, and also now available in India also. This beautiful Gymnocalycium mihanovichii nearly globose cactus available in red, orange, yellow or even pink colours is a result of single gene mutation resulting in loss of chlorophyll. As the plant can't survive without cholophyll, it needs to be grafted on another hardy compatible cactus, mostly a species of Hylocereus, which forms lower green portion of the cactus.
Here is var. friedrichi in orange yellow form now correctly named as Gymnocalycium stenopleurum, photographed from Garden of Five senses, Delhi, 22-2-2015.
Dr. Gurcharan Singh
Retired Associate Professor
SGTB Khalsa College, University of Delhi, Delhi-110007
Res: 932 Anand Kunj, Vikas Puri, New Delhi-110018.