Echinocactus platyacanthus

This is one of the largest cactus, nearly globular, broadly columnar, or barrel shaped, often very massive stems. It could live more than a hundred years and is easily recognized because of its massive size, by far the largest of all barrel cacti. They are day-flowering plants with vivid yellow flowers produced in spring and summer-autumn. Plants that flower in the spring and autumn, produce fruits in summer and winter respectively.

Frost tolerance: frost tender but resistant to 25 F / -4°C for short periods
Sun exposure: Full sun
Origin: Mexico
Growth habits: Stems often very massive 0.5-2.5(-3) metres high, 40-80(-100 or more) cm broad.Radial spines: (3-)4-8(-10), spreading, 1.2-4 cm long often in an upper and lower series

Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz