Tephrocactus geometricus f. crested


Tephrocactus geometricus f. crested hasn’t got synonyms, as it is a crested form. The synonyms of th regular species, Tephrocactus geometricus, are instead Opuntia geometrica and Tephrocactus alexanderi subsp. geometricus.


Tephrocactus geometricus f. crested is a nursery cultivar, and thus doesn’t exist in nature. The regular Tephrocactus geometricus, instead, thrives in high altitudes ranging from 2200-2900 metres above sea level, in the Argentina Catamarca and Bolivia border. It is able to survive in an extremely arid habitat and grows between tall red violet coloured rocks and gravel. The habitat is usually flat or moderately steep, and the soil it grows in is well-drained, clayey and sandy. The blazing hot sun is always present, leaving the plant fully exposed. Even though the vegetation in the area is generally sparse, Tephrocactus geometricus can be found growing amongst other species such as Puna bonnieae, Lobivia famatimensis v. bonnieae, Echinopsis leucantha, Pterocactus tuberosus, Cumulopuntia sp., Maihueniopsis sp. and Opuntia sulphurea.


Tephrocactus geometricus is a remarkable species that thrives in harsh desert environments. It has a small and compact size, and an underground habit of growth. This unique “opuntia” is highly sought-after by cacti enthusiasts due to its captivating, geometric appearance and stunning blooms. Its stem segments, in the regular form, are approximately 4-5 cm in diameter, and are clear glaucous/blue in color, which takes on reddish-purple hues when exposed to the sun. The new growing cladodes are dark purple. Although it has very few leaves, a caducuous white felt can be seen in young areoles. Unlike other cacti that have glochids, Tephrocactus geometricus does not have any or only has a few of them. Spines, on the other hand, are sporadically present in the upper areoles, and can range from 2-15 mm in length, white to black in color, thin or somewhat robust, flattened, appressed and turned downwards. Its flowers are typically white to light pink with a darker midstrip, and only last a day. The crested form, very rare in commerce, is very appreciated by cacti-enthusiast for its tiny, often heart-shaped stems, different and more wavy in shape than the typical fan-shaped crested cacti. The We remind that crested samples are unique: no specimen is identical to another, as they are the result of a genetic mutation that casually occurs in the plant cells. This mutation lead to a phenomenon called “fasciation”, that modifies the direction of cell division: normally, new cells are formed in all directions. In crested forms, instead, they are only generated in 2 opposite directions, perpendicularly to the axis of cellular division. This results into fan-shaped stems, flattened or more or less convoluted dependingo on the species and on the specific specimen. The other characteristic of Tephrocactus geometricus f. crested are similar to the regular T. geometricus, with the exception of the already mentioned stems and of the flowers, often absent in crested forms, as the genetic mutation alters the capacity of the plant to produce flowers.


Tephrocactus geometricus f. crested is not the easiest cacti to cultivate. It is rather sensitive to overwatering, but at the same time it requires enough water during the growth season. Due to its elongated fat taproot, it is best to use deep pots and well-drained mineral potting mix. It prefers full sun exposure, but excessive heat and sun in summer should be avoided. Choose filtered light, or either a position where it can have direct sun in early morning and late afternoon, avoiding the central, hottest hours of summer days. These cacti are slow growers and only produce a few new cladodes per year. They can tolerate light frost of up to -5 (-10) °C. During the winter rest period, they should be kept in a cool place but they must stay completely dry, to avoid rot. Without this cool winter period, they may not produce many buds. Keep them dry during winter to prevent rotting. It is essential to provide adequate air circulation.


Tephrocactus geometricus f. crested can be propagated by cuttings. Cut a part of the stem in spring, wait until a callous forms on the wound, and then place it on the surface of a sandy, well-drained substrate to be kept wet until new roots are formed. Grafting on more tough cultivars is also possible, such as other Opuntias


Tephrocactus is a type of cactus belonging to the family Cactaceae. The name is derived from the Greek word “tephra,” which pertains to the ash-like appearance of the plants’ skin. The name of the species, instead, “geometricus”, is derived from the Greek term ‘γεωμετρία’, meaning ‘geometry’. Its intricate, bluish-green stem boasts in facts a spherical form that eventually expands into rounded branches, hence the reference to geometry. Given enough exposure to sunlight or chilly fall temperatures, it may also exhibit a lovely purple hue.

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