Publication: Ashingtonia 3(5-6): 144. 1980 [1979 publ. 1980]
Description
Small clumping cactus with fine silvery spines arranged on globes so that it looks like orbs covered with small, white spiders. It readily forms a clustering mound.
The variety “Cajasensis” specifically describes the population from the Desfiladero de Cajas (altitude 2500 m) with orange-red or red flowers, larger heads with silvery pectinated spines. Some books state that Rebutia heliosa v. cajasensis looks pretty much like many of the forms of Rebutia heliosa v. condorensis but lighter spined. Indeed, some books make both these varieties synonymous, whereas.
Root: Tap root.
Stem: Grey green, 2-3(-4) cm wide, rarely higher than 4 cm.
Ribs: Spiraling with very tiny tubercles.
Areoles: Small, with brown felt and elongated.
Spines: only radials 2-4(-5) mm long, silvery white, pectinated, spider-like, covering almost completely the small stems in a spiral pattern.
Flower: Large dark-orange to red, funnel-shaped, long -necked, 4 cm in diameter, 5 cm long.
Blossoming time: Profusely flowering in spring.
Origin and Habitat
Cajas, Alto Cajas and Yesera, Mendez, Tarija, Bolivia.
Habitat: It grows in mountainous areas at an altitude around 2500 m 2800 m over sea level
Cultivation and Propagation
These plants come from mountainous areas, so like bright light, cool and dry conditions in the winter; this is important for the flowers as well as for their health. Without this cool winter period (0-10° C) they normally won’t get many buds. They have a thick taproot and are of difficult cultivation and rot prone because of a great sensitivity to the excess of watering, not easy to get to any large size on their own roots really a challenge to grow into a large clump. They are commonly grafted to avoid root problems and to make easier to grow. Sun Exposure: Suited for sunny-brightly exposure; can tolerate light shade.
Cultural Practices: Suited for airy exposures. Needs deep pot and good drainage to accommodate its tap root. It is very cold resistant as low as to -10° C or less for short periods of time. It is a fine plant for a rock garden or container, contrasts well with agaves, yuccas, and low-growing flowering plants.
Pests & diseases: R. heliosa is especially prone to root rot, therefore, underpot in a smaller container filled with very porous compost.
Propagation: Cutting as it branches freely from the base; Also can be grown from seeds or graft. Seeds can be sown in the spring or summer. The seedlings should not be disturbed until they are well rooted, after which they can be planted separately in small pots.
Bibliography
Major references and further lectures
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James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/Aug./2011
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David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006
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Edward F. Anderson “The Cactus Family” Timber Press, 2001
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