Family: Cactaceae

Native to mountainous regions of South America, these small to medium cactuses are generally globe-shaped. Many are solitary growers, while others produce offsets to form clumps. The stems are ribbed, and brightly coloured spines often protrude from the tubercles. The spines are variable and may be bristly and soft, or strong, and straight or hooked. The funnel-shaped flowers, which may be yellow, orange or red, protrude from the woolly crown of the plant, even when still quite young. (See also entry for Notocactus)

Species

P. aureispina is a medium-sized plant with notched ribs, yellow spines, the central one hooked, the others bristly, and golden yellow flowers, 4 cm (1½ in) in diameter.

P. chrysacanthion is a smaller type, densely covered with fine, yellow spines. The golden yellow flowers are only 2 cm (¾ in) in diameter.

P. maassii has a large number of spirally arranged ribs and yellow, needle-like spines. The flowers are a coppery or red colour 3 cm (1 in) across.

P. nivosa is a round to egg-shaped cactus, growing to only 15 cm (6 in) in height. Difficult to cultivate and frost-sensitive, it has a pure white, woolly crown and rich red flowers, to about 5 cm (2 in) in diameter.

P. penicillata is a large plant, about 30 cm (12 in) high, which has tufts of stiff white, yellow or brown spines and produces beautiful, red flowers. Its form becomes cylindrical with age.

Cultivation

These cactuses are easy to grow, but need an intermediate greenhouse or conservatory in frost-prone climates. Grow in pots of well-drained cactus compost. Provide maxi-mum light (but shade from direct strong sun), and a dry airy atmosphere. Apply water in moderation during the growing season, but keep dry in winter. Outdoors grow in well-drained soil and full sun but with shade during the hottest part of the day. Propagate in spring from seed germinated at 21°C (70°F).

Climate

Warmest parts of zone 9 and above.