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.
Ariocarpus bravoanus
Ariocarpus bravoanus is a species of cactus which is endemic to San Luis Potosí in Mexico. It grows in dry shrubland habitat on limestone substrates. It is endangered due to overcollecting.