€26,50

Tephrocactus geometricus (A.Cast.) Backeb. 

🌱 Morphology
   A slow-growing, compact, and sparsely branched cactus, formed by globose segments that detach relatively easily and can root when they come into contact with the soil. The segments, approximately 3–4 cm in diameter, have an almost spherical shape, with low, flattened tubercles that create regular polygons on the epidermis. Their color ranges from bluish-green and greenish-gray to purple tones, especially under intense light and in cool temperatures. The areoles are small, brown, and distributed on the upper part of the tubercles. In the type species, the spines are sparse, short, and often absent on the lower segments; in ‘Golden Thorn’, the trade name refers to the presence of golden-colored spines, although their stability and the origin of this selection have not been documented. The oldest segments may develop a cork-like surface due to lignification with age. The root system is thickened and adapted to arid environments; it may develop a fleshy taproot. A deep pot and balanced substrate are recommended.

🌍 Distribution, habitat, and family
A species endemic to Argentina, mainly in the province of Catamarca, where it grows in arid mountain environments on sandy, gravelly, and stony soils. Populations are known around Fiambalá and Loro Huasi, in landscapes with large temperature fluctuations, intense sunlight, and scarce rainfall. Some locations are above 2,300 m above sea level. Its globose growth habit and easily detachable segments favor survival and vegetative propagation in these environments. ‘Golden Thorn’ is a horticultural selection and does not have its own natural distribution.

Cactaceae family · Opuntioideae subfamily · Tephrocacteae tribe. It follows the taxonomy of Joël Lodé, which maintains Tephrocactus geometricus as the name in use. Opuntia geometrica A.Cast. is a nomenclatural synonym.

❄️ Temperature · USDA Zone 8b
It tolerates low temperatures of up to −9 ºC during dormancy if kept completely dry and properly acclimated. As a cultivation guideline, temperatures below −5 ºC should be avoided for potted specimens, as actual resistance depends on the duration of the frost, humidity, and the origin of the clone. Wet cold is especially dangerous for the roots and the junctions between the segments.

☀️ Lighting
It needs intense light to maintain the globose shape of the segments and promote bluish and purple tones. Very bright exposure is recommended, with gradual direct sunlight and good ventilation. If the golden spines are stable in this selection, adequate lighting will help highlight their contrast with the epidermis, although it has not been verified that light alone determines this coloration. During active growth, a reference of 18–25 mol·m⁻²·day⁻¹ of PAR DLI is recommended, with gradual acclimation if it comes from a shaded cultivation.

💧 Growth cycle and watering
Winter dormancy. Keep completely dry during the winter, especially in low temperatures. In spring and summer, water thoroughly and allow the substrate to dry out completely before watering again. It needs a balanced growing medium with excellent drainage and a pot that allows its roots to develop. Detached segments can root if placed on dry, airy substrate once any wound has healed.

🌸 Flowering
The species produces terminal flowers, generally white or pale pink, with a darker central band on the segments of the perianth. They reach approximately 3 cm in length and appear mainly during spring and summer, depending on growing conditions. The fruits are small, dry, and depressed, around 1.5–2.2 cm in diameter. 

🌿 Nutrition
During active growth, Desert CHOICE® Cactaceae NPK (Ca-Mg) 4-4-7 (4-4) is recommended. Assimilable calcium promotes the formation of firm tissues and the maintenance of turgidity, while magnesium participates in chlorophyll synthesis.

This is an inimitable xerophyte cultivated in Madrid in a technological square pot with substrate activated with mycorrhizal fungi and biofungicides.

Black gourmet pot of 9x9 cm

 * As this is an online purchase, the appearance of the sent specimen may vary slightly from the product image. The measurements of the plant are specified in the photo description, but this may also vary slightly, because it is a living being! Each of the plants at Desert CITY has unique characteristics.

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