Golden barrel cactus is valued for its striking bold, spherical habit and showy spines. It forms a broad, flattened, round barrel whose 20 or more vertical ribs are densely lined with golden yellow spines. Older plants are more cylindrical and younger more elongated. The barrel has a round, spineless, woolly spot at its top, which in summer gives rise to yellow flowers with numerous narrow, brown-tipped petals.