Stenocactus ARRIGENS

Stenocactus ARRIGENS - Ascending stenocactus, Stenocactus arrigens, Echinofossulocactus.

Stenocactus is a genus of cacti in the family Cactaceae, comprising about 10 species distributed in arid regions of central and northern Mexico. In nature, it occurs on stony limestone soils and often grows among spiny shrubs, which protects it from direct browsing by animals.

The genus is represented by plants with compact spherical or slightly cylindrical stems with numerous narrow, tall wavy and strongly corrugated ribs, which increase the surface of the stem for better absorption of sunlight and allow the plant to contract during drought. These ribs create an "accordion" effect and help retain moisture, imparting an ornamental appearance. The coloration of the stems varies from light to dark green; the surface is covered with small areoles bearing spines. The spines are slender, often curved or slightly interwoven; their coloration can be white, yellow, or brown.

Flowering occurs in spring and early summer. The flowers are funnel-shaped, medium-sized, located at the apex of the stem; the coloration of the petals varies from white to pink with a darker center. After flowering, dry oblong fruits form, containing small black seeds with a smooth or slightly rough surface.

Stenocactus arrigens is one of the species with beautiful spines. The stem is bluish-green, matte, spherical. In diameter, it is ten to thirteen centimeters (4-5.1 in). The ribs are thin with a wavy crest, numbering from fifty to sixty. The spines, radially arranged, are glassy white to yellowish, straight, slender. The length of the spines is one centimeter (0.4 in). Three central spines are colorless to yellow, the upper one two to four centimeters (0.8-1.6 in) in length. The flowers are about two and a half centimeters (1 in) in diameter and length; the petals are purplish-violet with a longitudinal dark stripe.

Before sowing, the seeds are soaked for several hours in warm water or for 5-10 minutes in a 3% hydrogen peroxide solution for disinfection. A drainage layer of 7-10 mm (0.3-0.4 in), a 2 cm (0.8 in) layer of loose mineral substrate (with the addition of sand and perlite), and a thin 1.5-2 cm (0.6-0.8 in) layer of washed river sand are successively poured into the planting container. Very small, dust-like seeds are distributed over the surface without embedding; larger ones can be lightly sprinkled or buried no more than 2-3 mm (0.08-0.12 in). Sowings are moistened from a spray bottle, covered with a transparent lid or film, and placed in a bright place at a temperature of 24-28 °C (75-82 °F) by day and 20-24 °C (68-75 °F) by night. Regular ventilation and maintenance of constant but not excessive moisture are necessary.

Seedlings emerge on average in 10-30 days; the minimum period can be a few days, and the maximum possible can be several months. Seedlings initially develop with two cotyledons, after which they form the first spines. They need bright indirect light and 8-12 hours of illumination. Pricking out is carried out after the first hair-spines begin to appear between the cotyledons or when the seedling diameter reaches about 1 cm (0.4 in). Further care consists of keeping in indirect light and moderate watering.

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In indoor conditions, bright illumination is used, optimally south and southwest windows. However, from direct sunlight on hot days the plant is slightly shaded, as in nature it grows under the cover of grasses and shrubs. With insufficient light, the stem stretches and loses ornamental appeal.

In summer, it is kept at a temperature of 20-25 °C (68-77 °F); watering is moderate, after complete drying of the soil ball. During the period of active growth, watering can be more generous, but no more than once every 1.5-2 weeks. In winter, a dormant period at 8-12 °C (46-54 °F) is necessary; watering is reduced to a minimum or stopped completely. In this case, it is desirable to provide supplemental lighting, otherwise flowering will not occur.

The substrate used is mineral, loose, with the addition of coarse sand or perlite, with a neutral or slightly alkaline reaction. A drainage layer is mandatory. Repotting is carried out annually for young plants and as needed for adults, usually once every 2-3 years. The new pot is taken only slightly larger than the previous one.

In spring and summer, fertilizers for cacti with low nitrogen content are applied approximately once a month. In winter, feedings are not used. Crown shaping is not required. Propagation is carried out by seeds sown in spring into a light mineral substrate.