Trichocereus Terschekii
family : Cactaceae
3cm tall in the picture
 
A columnar cactus native to south America (Argentina and Bolivia.) It can reach up to 10-15m in height. The Terschekii often plays host the ballmosses (Tillandsia spp)
 
Known as the Hedgehog Cacti or the Argentine Saguaro ( its a faster grower then the actual very iconic Saguaro cactus that we know the shape of thanks to spaghetti westerns.) 
 
The Terschekii can grow on a lot of different soil types such as grassland, shrubland and forestland.
Often towers over the vegetation in the area which is why it has been successful thus far. However it is abundant locally but the population is declining due to some very familiar hindereances such as agriculture, Urbanisation and over harvesting for its wood (wow) the cactus gets so thick and corks enough for it to have a woody enough stem to be harvested like a tree. how thick does it get well it can get up to 60cm in diameter. 
 
White impressive flower that can get to about 14cm wide. 
 
How low can you go frost tolerance wise this cacti can go as low as -9, as long as its dried out and only for short stints of time.