|Astrophytum myriostigma Description: A. myriostigma (many dotted) is a spineless plant, usually solitary or with very few basal branches. A transverse section of the stem reveal a perfect star shaped form (like the common star-fish) giving the plant the appearance of a bishop’s mitre (hence the common name Bishop’s cap)
Stem: Globular to cylindric up to 60(-100) cm tall (but usually about 150 cm tall) and 10-20 cm in diameter, bright green, covered with many minute white hairy scales that give it a characteristic chalk-white or silvery-grey appearance, but sometime naked. The scales are composed of very fine interwoven hairs, which, under a microscope, are very pretty object.
Roots: Fine, fibrous.
Areoles: Closed together
Ribs: Usually 5, sometimes 4(or 3) that increase to eight or more with age ( rarely even 10), vertical, regular, deep, prominent, very broad and acute.
Flowers: Funnelform, 4-7 cm long glossy yellow and sweet scented from the areole at the tip of the stem on mature plant. Outer perianth segments narrow, with brown scarious tips. Inner perianth segments numerous, oblong yellow with a silky shine. Scales on ovary tube scaroious, imbricated, very narrow often bristly tipped, with long wool in their axil.
Blooming season: Flowers appear intermittently throughout the warm months from April to September. Plants may take up to six years to flower.
Fruit: 2-2.5 cm in diameter, greenish to tannish-red Covered with brown, overlapping scales, with long wool in their axil.
Seeds: Dark brown, shining, with a large depressed hilum, the margins being turned in.
Cultivation: Although regarded as a choice and difficult plant in cultivation it is relatively easy to grow. It is sometime seen as a grafted plant but grows very well on its own roots too. Use mineral well permeable substratum with little organic matter (peat, humus). The Astrophytum myriostigma grows much faster with a low nitrogen content fertilizer in spring and summer. Water sparingly from March till October, the thin, fibrous roots suffer if there is humidity, therefore the plant should be watered only when the surrounding terrain is dry. Keep dry as soon as the temperature starts dropping in October and keep it perfectly dry in winter at temperatures from 5 to 15 degrees centigrade. (but it is Hardy to -7°C for short periods) Although it is one of the easier Astrophytum to grow, they tend to rot at that time of the year, if kept wet. In the rest period no high atmospheric humidity!! Sun Exposure: Light shade to full sun, its colour tends to richer and darker when grown in light shade.
Propagation: Almost exclusively by seed. Plants are sometimes grafted onto column-shaped cacti. Cutting scions from a flourishing plant is almost a crime because the scions do not root easily.
This quite variable plant has been widely grown for years and is now available in several cultivated variety and several breeds do exist. The famouse “Onzuka” is only one of these and though maybe the most beautiful, but a lot of other forms are represented in many collections.