Cleisto cactus

Cleistocactus strausii has a green stem that looks silvery grey because of the short, whitish spines that completely cover it. The columnar stem has about 25 low narrow ribs and each of the small, white areoles spaced at 2cm (0.8 inch) intervals along the ribs carries at least 30 thin, 2cm (0.8 inch) log white spines, together with 4 somewhat stouter, pale yellow ones that are up to 5cm (2 inch) long. The main stem often branches at the base, with upright-growing stems attached to the parent stem just above the surface of the potting mixture.
In a 20cm (8 inch) pot the plant can reach a height of 1.5m (5 feet) and will probably consist of several stems.