Cleistocactus strausii
The cactus prefers free draining soils, strong sunlight, but not high temperatures — in fact it can withstand hard frosts down to -10 °C. 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.
Cactus
By studying the ratio of C to C incorporated into a plant—its isotopic signature—it is possible to deduce how much is taken up at night and how much in the daytime. Using this approach, most of the "Pereskia" species investigated exhibit some degree of CAM-cycling, suggesting this ability was present in the ancestor of all cacti. "Pereskia" leaves are claimed to only have the C mechanism with CAM restricted to stems. More recent studies show that "it is highly unlikely that significant carbon assimilation occurs in the stem"; "Pereskia" species are described as having "C with inducible CAM." Leafless cacti carry out all their photosynthesis in the stem, using full CAM. , it is not clear whether stem-based CAM evolved once only in the core cacti, or separately in the opuntias and cactoids; CAM is known to have evolved convergently many times.