This is the cactus that we all see in Western films since we were children.  Huge, majestic with its spreading arms and a trade mark of the American desert. 

Carnegiea gigantea is a native of the Sonoran desert in the USA and the state of Sonora in Mexico.   It is the state flower of Arizona.  The plant grows slowly and can reach up to 13 meters in height and an age of 200 years.  It only starts to grow side arms at the age of 75 years old.  Mature Saguaros become a home for some birds that make their nests in holes they dig in the plants body.  In cultivation, the Saguaro needs well draining soil and is better left thirsty that overwatered.