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.
Fouquieria splendens
Ocotillo is not a true cactus. For much of the year, the plant appears to be an arrangement of large spiny dead sticks, although closer examination reveals that the stems are partly green. With rainfall, the plant quickly becomes lush with small (2–4 cm), ovate leaves, which may remain for weeks or even months.