Mammillaria SPINOSISSIMA

Mammillaria SPINOSISSIMA - Spiny pincushion cactus, Mammillaria spinosissima.

Mammillaria is a large genus of low-growing succulent plants in the cactus family (Cactaceae), comprising about 170-200 species distributed primarily in Mexico, as well as in the southern United States, Central America, the Caribbean region, and northern South America. In nature, representatives of the genus are found in deserts, semi-deserts, dry shrublands, tropical deciduous forests, on limestone slopes, rocky plains, and in mountainous areas with bright sun and well-drained soils.

The plants usually develop as solitary or clumping spherical, flattened-spherical, cylindrical, or short-columnar cacti. Instead of ribs, they have separate tubercles, or mammillae, on the tips of which are areoles with radial and central spines. In many species, wool, bristles, buds, flowers, and fruits form in the axils between the tubercles.

Flowers typically form in a ring near the apex of the stem and can be white, cream, yellow, pink, red, or purple. After pollination, elongated or club-shaped fruits develop, often red or pink, containing small brown or black seeds with a pitted or reticulated surface.

The spiny pincushion cactus has an oblong stem that becomes columnar with age, matte green, 20-25 cm (7.9-9.8 in) tall and 8-10 cm (3.1-3.9 in) in diameter, with conical tubercles. Axils have white pubescence and white bristles. There are up to 15 central spines; they are straight, elastic, of varying lengths, and exhibit variable coloration, occurring in shades of white, yellow, brown, or red. One of the central spines may be hooked at the tip. There are more than 20 radial spines; these spines are white, bristle-like, up to 1 cm (0.4 in) long. Flowers are up to 2 cm (0.8 in) long, ranging from pale pink to purple.

Mammillaria seeds are small, dark brown or black, rounded or slightly oval. Seed germination under careful greenhouse conditions is usually about 50-80%.

Sowing is carried out in spring or year-round if stable lighting is available. A sterile fine-grained mineral substrate based on sifted cactus soil, fine sand, perlite, and mineral chips is used. Seeds are distributed over the surface, lightly pressed into the moist soil, and covered with a minimal layer of fine sand or left uncovered. The sowing is moistened from a spray bottle with a weak solution of potassium permanganate or biofungicide with the addition of a growth stimulant: SUPERthrive, HB-101, Aminozol, Epin, or Zircon. The container is covered with a transparent lid or placed in a greenhouse.

Germination is carried out under bright diffused light and a temperature of about 22-26 °C (72-79 °F), without direct overheating under the sun. The surface is kept moderately moist, but not wet; moistening is performed only by fine spraying. Sowings are ventilated daily, and condensation is removed, since moisture stagnation is dangerous for mammillaria seedlings and quickly causes fungal damage.

The first sprouts may appear in 7-10 days; the usual germination period is 10-21 days, and the maximum possible period under temperature fluctuations or partial drying of the surface can stretch up to 4-6 weeks. After sprouts appear, the cover is gradually opened, and seedlings are kept under bright diffused light and careful moistening. Pricking out is performed after noticeable strengthening of the plants and the emergence of the first spines, usually no earlier than several months, with minimal damage to the roots.

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For cultivation, a maximally bright location is chosen with several hours of direct sun per day. Southern, southeastern, and southwestern windows are best suited, and supplemental lighting is recommended during the cloudy season. After a dark wintering or repotting, the plant is gradually acclimated to direct sunlight to avoid burns on the stem.

During the period of active growth, a temperature of about 20-28 °C (68-82 °F) is maintained with good air circulation. The plant is heat-loving and does not tolerate cold dampness. Wintering is kept bright, dry, and moderately cool, around 8-12 °C (46-54 °F), with nearly complete cessation of watering. At lower temperatures, moist substrate is especially dangerous and can cause root rot.

Watering is performed moderately, only after the substrate has dried out completely. In spring and summer, the soil is moistened in small portions, with mandatory drainage of water from the drip tray. In autumn, watering is gradually reduced, and in winter the plant is kept almost dry. Getting water into the axils between the tubercles is undesirable, especially in cool conditions and poor ventilation.

A loose mineral substrate for cacti is used with the addition of coarse sand, fine stone chips, pumice, zeolite, perlite, or other inert aerators. The organic component is added moderately. High drainage is laid at the bottom of the pot, and the container is chosen shallow, stable, and not overly spacious.

Fertilizer is applied only during the period of active growth, once every 4-6 weeks with a weak solution of fertilizer for cacti and succulents with reduced nitrogen content. Excess nutrients cause soft, loose growth and reduce resistance to rot. Repotting is carried out in spring as the pot becomes filled with roots; after repotting, the plant is kept without watering for several days. Pruning is not required, and separating side shoots is possible only on well-expanded specimens.