Publication: Succulenta (Netherlands) 74: 84. 1995
Description
Cleistocactus paraguariensis is a shrubby, sprawling cactus forming low clumps that produces nice zygomorphic flowers. It is generally included within (as a synonym of) Cleistocactus baumannii, suggesting that there is not really a fundamental difference between the two, and hard to name accurately without knowing where they come from. The name paraguariensis, meaning “of Paraguay”, refers to the origin of this plant.
Stems: Green, 10-15 cm in diameter, 10-15 mm thick, basally branching. Branches break off easily.
Ribs: 10-11, notched, ca 2 mm high, a little crenate
Areoles: Ovate ca 1,5 mm in diameter, almost black, becoming grey, 3-6 mm apart.
Radial spines: 12-15, yellow to reddish yellow with darker tips, the upper ones 2-6 cm long, the lower ones (shorter), 2-4 mm long.
Central spines: 4-5, reddish brown, the longer to 2.5 cm long, sometime only a few mm long.
Flowers: Zygomorphic, double-curved, orange-red, to 5 cm long barely open. Nectar chamber 5 mm long, 3 mm wide. Tube purple almost cylindrical, reddish brown with narrow yellowish to red scales, ca 1 mm long, and small white wolly hairs. Filaments white red above, anthers lilac. Petals 9 mm long, 3 mm wide, red, erect, spreading out of the corolla about 8 mm. Style white, stigma lobes c. 7 yellowish-green.
Origin and Habitat
Paraguari department, Paraguay.
Habitat and ecology: This specie grows in rock mountain and is quite rare.
Cultivation and Propagation
Cleistocactus baumannii var. paraguariensis is a a much decorative hardy cactus.
Growth rate: This species grows rapidly enough to need pruning.
Soil: Grow it in a rich and particularly draining substratum, as it is very sensitive to rottenness when in presence of humidity and low temperatures and let the soil dry out between waterings.
Water: In summer, during the vegetative period, it must be regularly watered, but allowing the substratum to completely dry up before irrigating again; in winter, it’s to be kept dry. Preferable not to water on overcast days, humid days or cold winter days.
Hardiness: This is one of hardiest of the woolly columnar cacti from Bolivia that grow at an altitude of up to 1000 meters. It is a frost resistant cactus, hardy to -7°(or even less if very dry). However in cultivation it is better not to expose it to temperatures lower than 0° C, even if in an aerated and protected location, in order to avoid the formation of anti-aesthetic spots on the epidermis. In presence of high atmospheric humidity avoid any frost as it is particularly sensitive to root rot.
Exposure: It need full sun exposures with ample airflow to produce dense hairs, but, as a former mountain dweller, does not care for extremely high temperatures in summer.
Maintenance: Repot in the spring, when their roots become cramped. Generally, they should be repotted every other year in order to provide fresh soil. After repotting, do not water for a week or more.
Use: Excellent as landscape or patio plant. It is suitable for small “desert” gardens, in association with other xerophytes. Where the open air cultivation is not possible due to the climate, it is to be cultivated in pot in order to shelter it in winter.
Propagation: By seeds and by cuttings, provided left drying up well, in summer.
Bibliography
Major references and further lectures
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Edward F. Anderson “The Cactus Family” Timber Press, 2001
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Friedrich Ritter “Kakteen in Südamerika - Ergebnisse meiner 20jährigen Feldforschungen: Brasilien / Uruguay / Paraguay”, Volume 1 Selbstverl., 1979
