The Golden Barrel Cacti is one of the most recognized cactus. In the wild it is rare and endangered, but is one of the most cultivated cacti by plant nurseries for consumers. These are highly desirable for planting in containers and garden landscapes. Their life can be as long as 30 years and when mature they grow clustering barrels like above. The official name for this cactus is Echinocactus Grusonii.
This was photographed in the desert garden at the Huntington Library in San Marino, California.
Mature plants will have small yellow flowers around the crown. This is a flower on my Golden Barrel of about 8 yrs old. The size of the barrel is about 24 inches in diameter.