Notocactus SCOPA - Silver ball cactus, Broom notocactus, Notocactus scopa, Parodia.
Notocactus is a genus of plants in the cactus family (Cactaceae), which modern taxonomy has entirely included in the genus Parodia. The name Notocactus remains in wide use, however, and seeds are almost always sold under it.
In nature, these cacti grow on highlands and in the foothills of Paraguay, Southern Brazil, Argentina, and Uruguay. Their stem is solitary, short-cylindrical or globose, up to 1 m (3.3 ft) high in adult specimens, dark green, with well-defined ribs. Most species do not form branches or offsets. On the crests of the ribs sit numerous small tubercles with pubescent areoles, from which emerge clusters of spines: from 1 to 5 brownish-red central and up to 40 short yellow radial ones.
Notocacti bloom early and very abundantly, with flowers large relative to the size of the plant. They form in the upper part of the stem or right at the apex. The flower is polypetalous, bell-shaped or funnel-shaped, and the thick short fleshy floral tube is densely covered with spines and bristles. The coloration can be yellow, orange, or red, petal bases are usually contrasting or more saturated, and stigmas are more often reddish. An open flower lasts about a week.
Silver ball cactus is a species with a bluish cylindrical stem up to 30 cm (12 in) high and 10 cm (4 in) across, branching from the base. Numerous ribs are densely set with short pure white spine-bristles, 30-40 in each areole, among which stand out 3-4 central ones, more robust and brightly colored. In different forms of the species they are dark red, almost black, bright yellow, or cream, and the cactus looks like an elegant contrasting fine-bristled ball.
The flowers are diurnal, numerous, lemon-yellow, 3.5 cm (1.4 in) long and up to 5 cm (2 in) across, with a red pistil, blooming at the apex of the stem. The floral tube is short, covered with fine hairs and bristles. This species is often grafted onto a tall rootstock.