Cleistocactus Strausii
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''Cleistocactus strausii'', the silver torch or wooly torch, is a
perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...
flowering plant in the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Cactaceae A cactus (: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (), a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. The word ''cactus'' derives, through Latin, ...
. It is
native Native may refer to: People * '' Jus sanguinis'', nationality by blood * '' Jus soli'', nationality by location of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Nat ...
to mountainous regions of Department Tarija, Bolivia, at .


Description

''Cleistocactus strausii'' grows as a shrub, slender, erect, branches out from the base with several upright, with gray-green columns growing up to tall, but only about across, which are covered in white spines. The light green shoots reach a diameter of up to 8 cm (3.1 in) and are completely covered by dense, white spines. There are 25 to 30 ribs and are densely covered with
areole In botany, areoles are small light- to dark-colored bumps on cactus, cacti out of which grow clusters of Thorns, spines, and prickles, spines. Areoles are important diagnostic features of cactus, cacti, and identify them as a family distinct fr ...
s, supporting four yellow-brown
spine Spine or spinal may refer to: Science Biology * Spinal column, also known as the backbone * Dendritic spine, a small membranous protrusion from a neuron's dendrite * Thorns, spines, and prickles, needle-like structures in plants * Spine (zoology), ...
s up to long and 20 shorter white
radial Radial is a geometric term of location which may refer to: Mathematics and Direction * Vector (geometric), a line * Radius, adjective form of * Radial distance (geometry), a directional coordinate in a polar coordinate system * Radial set * A ...
s. The approximately 4 central spines are light yellow and up to 2 centimeters long. The 30 to 40 white radial spines are hairy to bristly and 1.5 to 5 centimeters long. Older cacti, over tall, produce tubular flowers in late summer. They are deep red to burgundy and grow up to long cylindrical flowers protrude horizontally and radially from the stem of the cactus.The flower-tube is very densely covered with silky hairs. The pear to spherical, red fruits reach a diameter of up to 2 centimeters. In common with other cacti in the genus '' Cleistocactus'', the flowers hardly open, with only the
style Style, or styles may refer to: Film and television * ''Style'' (2001 film), a Hindi film starring Sharman Joshi, Riya Sen, Sahil Khan and Shilpi Mudgal * ''Style'' (2002 film), a Tamil drama film * ''Style'' (2004 film), a Burmese film * '' ...
and
stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...
s protruding.


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 A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...
.


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. This cactus prefers free draining soils, strong sunlight, but not high temperatures; in fact it can withstand hard frosts down to . 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 Root rot is a condition in which anoxic conditions in the soil or potting media around the roots of a plant cause them to rot. This occurs due to excessive standing water around the roots.-Hydroponics Root Rot: What is It, How To Treat It, How ...
. Cultivated plants often flower freely. In the United Kingdom, this plant is usually grown under glass, and has gained the
Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr ...
's
Award of Garden Merit The Award of Garden Merit (AGM) is a long-established award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. It includes the full range of cultivated p ...
.


Pests

The silver torch cactus is most susceptible to
mealybugs Mealybugs are insects in the family Pseudococcidae, unarmored scale insects found in moist, warm habitats. Of the more than 2,000 described species, many are considered pests as they feed on plant juices of greenhouse plants, house plants and su ...
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.


Gallery

File:Cleistocactus strausii (70387).jpg Cleistocactus strausii pm.jpg Cleistocactus strausii 5.jpg


References

*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 *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/


External links

* *
University of Connecticut Ecology department
{{Taxonbar, from=Q144921 strausii Cacti of South America Flora of Bolivia Flora of the Andes Garden plants of South America