Astrophytum MYRIOSTIGMA 'STRONGYLOGONUM-SMYLE' Nuda, Japan

Astrophytum MYRIOSTIGMA 'STRONGYLOGONUM-SMYLE' Nuda - Round-ribbed naked bishop's cap 'Smile', Astrophytum myriostigma strongylogonum, Many-ribbed astrophytum.

Astrophytum is a genus of succulent plants in the family Cactaceae, comprising 6 species and numerous cultivars and forms growing on rocky and calcareous soils in the foothills and mountains of northeastern Mexico and Texas.

Representatives of the genus are known for solitary, spherical or cylindrical, ribbed bodies and a virtually complete absence of spines, although some species do possess a few curved spines. The surface can be smooth or covered with white flecks forming unusual, light, felt-like, marbled patterns on the stem surface capable of absorbing moisture. Leaves are absent; the body of the plant is green, often with a glaucous bloom, adorned with areoles bearing spines.

The cacti grow very slowly, but bloom early with large, funnel-shaped, yellow flowers, sometimes with a red center, located at the apex of the stem. The flowers usually wither after a couple of days. With proper care, flowering lasts for a prolonged period, from spring until late autumn. Fleshy pubescent fruits with thin skin contain black or brown seeds.

Astrophytum myriostigma strongylogonum nuda 'Smile' is a unique cultivar with an elongated, cylindrical body devoid of characteristic flecking. The surface is smooth, uniformly green. The ribs are broad, rounded, slightly spiraled, giving the plant an unusual appearance. The name 'Smile' is associated with the original visual appearance of the form and often varies in growth vigor and rib thickness.

It blooms in spring and summer. The flowers are funnel-shaped, yellow, large, up to 6 cm (2.4 in) in diameter, appearing at the crown. Flowering can repeat with good care. The fruits are oval, reddish, pubescent, dehiscing upon ripening.

Before planting, seeds are soaked for 3-6 hours in warm water with the addition of stimulants (SUPERthrive, HB-101, Aminozol, Epin, or Zircon), after which they are disinfected for 10 minutes in a weak solution of potassium permanganate, then air-dried and sown on the surface of a moist substrate consisting of leaf mold, river sand, and finely crushed charcoal in a 1:1:1 ratio. They are moistened with a spray bottle, covered with film or placed in a propagator, and germinated in the light, but not in the sun, at a temperature of 20-25 °C (68-77 °F), with a nighttime temperature drop to 15-18 °C (59-64 °F) desirable. Regular ventilation is carried out and uniform moisture is maintained.

Seedlings appear within 10-30 days, depending on temperature and humidity. The maximum germination period can exceed 45 days. Caution with watering must be observed so as not to ruin the sprouts. Pricking out is carried out upon the appearance of 2-3 true tubercles, after which the plants are transplanted into individual containers. The seedlings, somewhat larger than those of other globose cacti at this stage, develop slowly but steadily. Flowering occurs in the 4th-6th year if dormancy regime and good illumination are maintained.

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The plant is placed in a sunny spot, preferably on a south or southwest window. Access to fresh air and the absence of moisture stagnation are provided. The temperature in summer is maintained at 22-30 °C (72-86 °F). In autumn, the plant is prepared for dormancy, and by winter the temperature is smoothly lowered to 10-12 °C (50-54 °F) with complete rest.

Watering is carried out moderately after the substrate dries out, thoroughly soaking the root ball with water. In the winter period, watering is excluded. With the onset of the growing season, the ambient temperature is gradually raised above 12 °C (54 °F); at temperatures below this, the plant is incapable of absorbing water. The first watering is performed carefully and with a small amount of water.

For growing, a stable and shallow pot with an obligatory drainage layer is selected. A mineral substrate with the addition of sand, gravel, and brick chips is used. Repotting is carried out in spring, carefully, trying not to damage the root system, since new roots regenerate with difficulty. The astrophytum is potted on into a container only slightly larger, just enough to accommodate it. Repotting is carried out from dry soil to dry soil, and watering is done after 5-7 days so that damaged roots dry out. Mature plants, starting from 10 years of age, are repotted rarely, at intervals of 5-6 years and only if roots entwine the entire root ball.

During the growing season, once every 4 weeks, plants are fed with special fertilizers for cacti with reduced nitrogen content in a diluted concentration. Feedings are not applied during dormancy. Plants do not tolerate elevated calcium content in the soil well. Shaping is not required. Propagation is carried out by seeds. Offsets are not formed.