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.
Ferocactus
"Ferocactus" have very shallow root systems and are easily uprooted during flash floods. The "fishhook" spines and the armored web of spines enclosing the cactus body in many species of this genus are adaptations which allow the plant to move to more favorable locations. The seeds germinate in areas where water movement occurs or in areas where standing water accumulates for some period of time, and during flash floods, the hooked spines allow the plants to be caught on waterborne debris, uprooted and carried to areas where water tends to accumulate.