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.
Eucalyptus camaldulensis
Regulation causes flooding to be decreased during the winter and spring months, and water more consistently flows during the summer and autumn months. Since the river red gum disperses its seed during spring, regulating the water may affect the species' ability to disperse using water as a dispersing agent, especially in floodplain red gum forests. Natural water run-off can also be affected, leaving some trees permanently flooded due to the build-up of water behind dams, or the permanent water flow. Neither can seeds germinate in constantly flooded areas.