
Strombocactus disciformis subs. jarmilae Photo by: Valentino Vallicelli
MMR 114.1 Vizarron, Querétaro, Mexico
: Northern Mexico (Querétaro and Nuevo León)
Altitude: Around 1400-1500 metres above sea level.
Habitat: Strombocactus disciformisSN|2109]]SN|2103]] grows in central Mexico in shadow localities, often in crevices on vertical gypsum canyon-walls fulfilled with acidic soil. On the contrary the northernmost Strombocactus jarmilaeSN|2103]]SN|2109]] grows on limestone and likes more alkaline soils and full sun exposures.
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: Strombocactus jarmilaeSN|12844]]SN|2109]] is a slow-growing, miniature taxa of doubtful validity, generally included in Strombocactus disciformisSN|2103]]SN|2103]]. It is appears to have a smaller body, with small flowers, long thin spines and some other minor differences. It blooms profusely, and starts flowering at an early stage of development when only 1 cm in diameter.
Habit: It is a geophytic plant, usually solitary, deep-seated, that flush with soil surface in habitat.
Stem: The body is flattened or spherical, not bigger than 4 cm in diameter (S. disciformis may reach 20 cm in age, and 3 to 9 cm across). The crown is slightly depressed and felted. The colour is blue-green with greyish tinge, the base covered with brown corky spots in age.
Tubercles: S. jarmilae has characteristic rhomboid tubercles other than those of S. disciformis and of Strombocactus pulcherrimusSN|2109]]SN|12844]]. They are firm, spirally arranged and imbricate, less than 1 cm tall. These tubercules are flattened and almost truncated above and somewhat horny or keeled below.
Spines: 4 to 5, erect, somewhat thinner, dark grey at the tips and pale grey at the base, up to 2 (or more) cm long, becoming calcified and in age falling at the stem base.
Roots: It has a thin central root and not the strong napiform root typical of S. disciformis.
Flower: Flowers of S. disciformis are larger and more fleshy, those of S. jarmilae are thin, smaller, and dehydrated soon. One to several arise on the crown, measure about 3 cm in length and breadth, are cream coloured.
Fruit: 7 mm across, splits down its length.
Seeds: Dust-like, very small, S. disciformis has nearly 2 times bigger seeds with pressed hilium, S. jarmilae has oval-shaped hilium.
Blossoming time: Flowers emerge early in spring and are freely produced throughout the summer, remaining open for 1-2 days.
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Strombocactus disciformis subs. jarmilae Photo by: Valentino Vallicelli
Strombocactus disciformis subs. jarmilae Photo by: Valentino Vallicelli
Strombocactus disciformis subs. jarmilae Photo by: Valentino Vallicelli
Strombocactus disciformis subs. jarmilae Photo by: Valentino Vallicelli
Strombocactus disciformis subs. jarmilae Photo by: Valentino Vallicelli
Strombocactus disciformis subs. jarmilae Photo by: Valentino Vallicelli
Strombocactus disciformis subs. jarmilae Photo by: Valentino Vallicelli
: It is relatively easy to grow, but very slow growing. It is often seen as a grafted plant but grows very well on its own roots too. Needs a very well drained mineral substratum with little organic matter (peat, humus). Requires strong sun to part sun to develop good compact growth and waterings should be rather infrequent, to keep the plant flat shaped and not become excessively elongated and unnatural in appearance. Use Water sparingly from March till October and keep perfectly dry in winter, or when night temperatures remain below 10° C (but some people give this plant a light monthly watering to prevent the drying and shedding of the lower tubercles.) It is hardy to -4°C (or less) for a short period. In the rest period no high atmospheric humidity!! Ensure a good ventilation.
Propagation: Almost exclusively by seeds. But the seedlings are tiny and very slow growing and at first they take one or two years to reach the diameter of 1 mm!!! Once they have reached 4 years old or more they are relatively easy to grow, the problem is getting them to 4 years old! Than they reach 2 cm of diameter in about 6/8 years, and require very careful watering. Plants need 8 to 10 years to reach the flowering size.
Sometime, older specimens may shoot tillers from under tubercles, so they can be propagated by cuttings in spring (but rooting may prove a challenge). Plants are sometimes grafted onto column-shaped cacti, which is a much easier way of propagation than sowing.
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