Astrophytum ASTERIAS 'KULTUR NUDUM' - Naked star cactus 'Kultur Nudum', Astrophytum asterias 'Kultur Nudum'.
Astrophytum is a genus of succulent plants of the family Cactaceae, comprising 6 species and many cultivars and forms growing on rocky and limestone 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 virtually no spines, although some species do have a few curved needles. The surface can be smooth or covered with white flecks forming unusual, pale, felted, marble patterns on the stem surface capable of absorbing moisture. There are no leaves; the plant body is green, often with a glaucous bloom, adorned with areoles and spines.
The cacti grow very slowly, but bloom early with large, funnel-shaped, yellow flowers, sometimes with a red center, located at the top of the stem. The flowers usually wither after a couple or three days. With proper care, flowering lasts for an extended time, from spring to late autumn. Fleshy, pubescent fruits with thin skins contain black or brown seeds.
Astrophytum asterias belongs to the type of "naked" cacti (lacking spines); it has a spherical, slightly flattened stem reaching 8-10 cm (3.1-4 in) in diameter and 6-8 cm (2.4-3.1 in) in height. On its surface, 6-8 faintly pronounced ribs are visible. Axillary buds (so-called "areoles") are located in the middle of the ribs. Nearby are white spots that give the cactus surface special decorativeness. Overall, the cactus resembles a sea urchin skeleton. The diameter of its silky yellow flowers is 6-7 cm (2.4-2.8 in), and their length is 3 cm (1.2 in). Their center may have a reddish tint.
Flowering begins relatively early. Flowers usually open in early summer during daytime hours. Cacti growing in a sunny place acquire a characteristic bronze hue over time. This species easily forms hybrids with Astrophytum myriostigma.