The classic Bishop's Cap. This is a green bodied cactus covered with white flecking. It takes full sunlight and blooms yellow right at the apex. This species is extremely variable even to the number of ribs and can change from 4 to 5 to 6 or more as it grows and occasionally reduces the rib numbers as it matures. Very slow growing and quite hardy through light frosts if planted where it does not stand in wet soils.
These came from a rather surprising source: a green grower who dabbled in cactus and forgot he had these for several years. We bought all he had and are delighted to have them as our own are several years from getting to this size. They take full sun and the yellow blooms cycle several times each season in our climate.