Cleistocactus straussi

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Ordo: Caryophyllales

Familia: Cactaceae
Subfamilia: Cactoideae
Tribus: Cereeae
Subtribus: Trichocereinae
Genus: Cleistocactus
Species: Cleistocactus strausii
Name

Cleistocactus strausii (Heese) Backeb., 1934
Note

The epithet of the species honors L. Straus (1862–1934), a German merchant and cactus lover from Bruchsal and co-founder of the German Cactus Society.
Synonyms

Borzicactus strausii (Heese) A.Berger
Cephalocereus straussii (Heese) Houghton
Cereus strausii (Heese) Vaupel
Denmoza strausii (Heese) Fric
Echinopsis nothostrausii Anceschi & Magli
Pilocereus strausii Heese
Pilocereus strausii f. cristatus Dörfl.
Cleistocactus nivosus Borg, Cacti, ed. 2: 195. 1951 syn. sec. Kiesling & al. 2014

Distribution
Native distribution areas:

Continental: Southern America
Regional: Western South America
Bolivia (Tarija).
Introduced into:
Canary Is.

References: Brummitt, R.K. 2001. TDWG – World Geographical Scheme for Recording Plant Distributions, 2nd Edition
References
Primary references

Backeberg, C. 1934. Kakteen-Freund; illustrierte Monatsschrift für Kakteenliebhaber. Deutsche Kakteen-Zeitung 3: 121

Additional references

Verloove, F. & al. (2017). New records of naturalised and invasive cacti (Cactaceae) from Gran Canaria and Tenerife, Canary islands, Spain Bradleya. Yearbook of the British Cactus and Succulent Society 35: 58-79.
Lowry, M. (2016). A synopsis of the genus Cleistocactus Lemaire (Cactaceae) Bradleya. Yearbook of the British Cactus and Succulent Society 34: 148-186.
Govaerts, R. 1999. World Checklist of Seed Plants 3(1, 2a & 2b). 1532 pp.. MIM, Deurne. ISBN 90-5720-098-8 (issue 1), ISBN 90-5720-099-6 (issue 2b). Reference page.
Korotkova, N., Aquino, D., Arias, S., Eggli, U., Franck, A. , Gómez-Hinostrosa, C., Guerrero, P.C., Hernández, H.M., Kohlbecker, A., Köhler, M., Luther, K., Majure, L.C., Müller, A., Metzing, D., Nyffeler, R., Sánchez, D., Schlumpberger, B. & Berendsohn, W.G. 2021. Cactaceae at Caryophyllales. org–a dynamic online species-level taxonomic backbone for the family. Willdenowia 51(2): 251–270. DOI: 10.3372/wi.51.51208 Open access Reference page.

Links

Korotkova, N. et al. 2021. Cleistocactus strausii in Cactaceae at Caryophyllales.org. A global synthesis of species diversity in the angiosperm order Caryophyllales. Published on the internet. Accessed: 2021 Dec 07. Reference page.
Govaerts, R. et al. 2021. Cleistocactus strausii in Kew Science Plants of the World online. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the internet. Accessed: 2021 Apr 20. Reference page.
International Plant Names Index. 2021. Cleistocactus strausii. Published online. Accessed: Apr 20 2021.
Tropicos.org 2021. Cleistocactus strausii. Missouri Botanical Garden. Published on the internet. Accessed: 2021 Apr 20.
Hassler, M. 2021. Cleistocactus strausii. World Plants: Synonymic Checklists of the Vascular Plants of the World In: Roskovh, Y., Abucay, L., Orrell, T., Nicolson, D., Bailly, N., Kirk, P., Bourgoin, T., DeWalt, R.E., Decock, W., De Wever, A., Nieukerken, E. van, Zarucchi, J. & Penev, L., eds. 2021. Species 2000 & ITIS Catalogue of Life. Published on the internet. Accessed: 2021 Apr 20. Reference page.

Vernacular names
Deutsch: Silberkerzenkaktus
English: silver torch cactus, wooly torch
svenska: Silverpelare

Cleistocactus strausii, the silver torch or wooly torch, is a perennial flowering plant in the family Cactaceae. It is native to mountainous regions of Department Tarija, Bolivia, at 1,500–3,000 m (4,921–9,843 ft).

Its slender, erect, grey-green columns can reach a height of 3 m (9.8 ft), but are only about 6 cm (2.5 in) across. The columns are formed from around 25 ribs and are densely covered with areoles, supporting four yellow-brown spines up to 4 cm (1.5 in) long and 20 shorter white radials.

This cactus prefers free draining soils, strong sunlight, but not high temperatures; in fact it can withstand hard frosts down to −10 °C (14 °F). In its natural habitat it receives plenty of water during the summer, but almost none over the winter. In cultivation, watering too much in winter often leads to root rot.

Older cacti, over 45 cm (17.5 in) tall, produce deep red, burgundy, flowers in late summer. The 6 cm (2.5 in) long cylindrical flowers protrude horizontally and radially from the columns. In common with other cacti in the genus Cleistocactus, the flowers hardly open, with only the style and stamens protruding. Cultivated plants often flower freely. In the United Kingdom, this plant is usually grown under glass, and has gained the Royal Horticultural Society's Award of Garden Merit.[1]

Description

Cleistocactus strausii has gray-green columns growing up to 3 m (9.8 ft) tall and several centimetres in diameter, which are covered in white spines. Only older plants will produce the deep red/burgundy cylindrical flowers. These flowers emerge horizontally and radially from the stem of the cactus. They are deep red to burgundy and grow up to 10cm long.
Habitat

Cleistocactus strausii prefers mountainous regions that are dry and semi-arid. Like other cacti and succulents, it thrives in porous soil and full sun. While partial sunlight is the minimum requirement for survival, full sunlight for several hours a day is required for the silver torch cactus to bloom flowers.

Silver torch cacti can thrive in low-nitrogen soils without facing the consequences. Too much water will make the plants weak and lead to root rot.
Conservation status

This cactus is locally abundant in its native land and has few local threats to its survival, so it is rated Least Concern.
Propagation

It can be propagated by cuttings or seed. Cuttings should be taken near the base of the main stem, similar to cuttings for aloe vera. Rooting of this new cutting usually occurs within 3-8 weeks, therefore it is usually better to propagate silver torch cactus via seed.
Pests

The silver torch cactus is most susceptible to mealybugs and spider mite.

Mealybugs are among the most common pests of cacti and succulents. They can be identified by their white, cottony masses on the plant. These are signs that the bugs are reproducing. These pests are especially problematic because they suck out plant sap, depleting the strength of the plant. They can also cause sooty mold along with their fluffy white wax, detracting from the plants'appearance. Another form of mealybug attacks the root system of plants, which is harder to detect.

Mites thrive in the same hot, dry conditions that the silver torch cactus lives in. Spider mites cause damage by sucking out vital nutrients from the plant. Large populations of mites can cause irreversible damage, eventually killing the plant.

However, both pests can be hosed off with water.

References

"RHS Plant Selector Cleistocactus strausii AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2020-04-17.

W. (2016, December 27). Cleistocactus strausii - Silver Torch Cactus. Retrieved April 16, 2018, from https://worldofsucculents.com/cleistocactus-strausii-silver-torch-cactus-snow-pole/
Mealybugs in the Greenhouse. (n.d.). Retrieved April 16, 2018, from https://content.ces.ncsu.edu/insect-and-related-pests-of-flowers-and-foliage-plants/mealybugs-in-the-greenhouse[permanent dead link]
Silver Torch Cactus. (n.d.). Retrieved April 16, 2018, from https://web.archive.org/web/20171014004620/http://www.horticultureunlimited.com/plant-guide/silver-torch-cactus/
Silver Torch Cactus - Cleistocactus strausii - Overview. (n.d.). Retrieved April 16, 2018, from http://eol.org/pages/5188261/overview
Plants & Flowers. (n.d.). Retrieved April 16, 2018, from https://web.archive.org/web/20181019164012/http://www.plantsrescue.com/tag/silver-torch-cactus/