Cleistocactus strausii
Silver Torch cactus can thrive in low-nitrogen soil without facing the consequences of low nitrogen. Too much water will make the plant weak and lead to root rot. 
Least Concern. This cactus is locally abundant in its native land and has few local threats to its survival.
This cactus can be propagated by cuttings or seed.
Echinomastus mariposensis
Threats to this rare species have included mercury mining, petroleum exploration activities, off-road vehicles, and grazing. The worst threat has been poaching by cactus collectors. The collectors employed professional diggers to go into the habitat and retrieve this and other species of cacti, which were stockpiled, shipped away for sale, and sometimes discarded or wasted. The type locality of the cactus has been scoured for specimens and few are found there anymore. Plants in Big Bend National Park occur on rugged terrain and have generally been safe from collectors. In 1983 the cactus was placed on Appendix 1 of CITES in an effort to protect it from harvesting.