Found in Eastern Bolivia and Argentina, Cereus validus is a handsome branching blue grey columnar to 14 feet tall. Like other Cereus it's white to pink flowers are nocturnal. With age it can take on a segmented appearance much like Armatocereus.
     I got a cutting of this from a vacant property in Tucson. And I'm glad it's a pink flowered one. I was also glad it had enough energy in the unrooted cutting to flower. At first I had it miss-identified as Armatocereus which has much smaller flowers.

Closeup of the flower bud	Open a few nights later	A view from the side	A nice big one by a building in Tucson
A closer view