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.
San Andreas Creek
Fog drip may play a key role in the precipitation in the upper watershed. On Cahill Ridge (just west of San Mateo Creek and east of Pilarcitos Creek, at an elevation of , Oberlander measured fog drip beneath tanoak ("Lithocarpus densiflorus"), Coast redwood and three Douglas fir trees, the latter tall. He found that the trees most exposed produced the most precipitation and in five weeks of measurement (July 20 – August 28, 1951) fog drip below the tanoak produced of precipitation, more than the total annual precipitation on nearby grasslands and chaparral. The Douglas fir produced of fog drip and appeared to provide unique conditions supporting the orchids giant helleborine ("Epipactis gigantea") and phantom orchid ("Cephalanthera austiniae"), since these plants were found exclusively in these moist ridge tops.