Cleistocactus strausii
As a houseplant, the Silver Torch cactus is an easy to take care of so long as over-watering is avoided. To naturally simulate the porous effects of the sand in its native habitat, it's important to ensure that excess water will not pool in the soil, causing the roots to become water logged.
This plant’s native habitat does not have winter, but when temperatures drop to the low twenties, it can exhibit signs of tip frost. 
The Silver Torch cactus is most susceptible to 
mealybugs 
and spider mite.
Opuntia aciculata
Like its other cactus relatives, this deciduous and succulent species also has it leaves reduced to spines to reduce excess transpiration, which helps it to survive by conserving water in the hot climate of Texas, in southwestern United States, and North Mexico. This adaptation also helps in defending itself from being consumed by any herbivores there. It has the special ability to propagate from woody or softwood stem cuttings. It can even propagate by cuttings of leaf pads at any time in the growing season, allowing the cut surface to callus over before planting. This cactus can survive healthily and produce good many flowers only if it is fully exposed to the sun. They can also tolerate temperatures from −5 to −12 °C.