Painted barrel Cactus:

This architectural beauty is a signature cactus of the Southwest desert. The golden barrel is considered a rare and endangered species. It grows slowly to three feet high and spreads two feet wide. At maturity, yellow blossoms appear at the top of the plant in spring. This can vary greatly depending on the type of barrel cactus you have. However, a general rule of thumb is to provide your cactus with approximately six to eight hours of sunlight exposure every day.