Native to North America and Mexico, these big, barrel-shaped, slow-growing cactuses have strong spines on acute ribs, flattened at the apex and woolly where the flowers appear. The short, funnel-shaped, sometimes self-fertile flowers open by day and close by nightfall. Tube, ovary and fruit are woolly and scaly.

Species

E. grusonii, golden ball or golden barrel, from Mexico, is a huge, globe-shaped cactus, to 1 m (3 ft) tall and up to 80 cm (32 in) across. It has long, strong, golden spines, rather thin ribs and yellow flowers, up to 6 cm (2� in) long, which grow in a circle from the woolly areoles at the plant's top.

E. platyacanthus (Synonym: E. ingots) is a large, grayish green plant, to 1.5 m (5 ft) high and about 1 m (3 ft) across, with up to 50 high, rounded ribs and very sharp spines, 3-4 cm (about 1� in) long. It has a woolly apex from which emerge yellow flow�ers, 20 mm (1 in) in diameter.

Cultivation

In frost-prone climates, grow in an airy, intermediate greenhouse or conservatory, in pots of cactus compost, obtainable from garden centers. Provide maximum light and do not water plants in winter. Outdoors, grow in a sunny spot with well-drained soil. Propagate from seed in spring, in a warm propagating case.