Cane Cactus

Austrocylindropuntia cylindrica (aka Cane Cactus): A robust, shrubby cactus of branching stem segments. Its dark green stems have rhomboid tubercles and white areoles and spines. The stems can be topped with tiny (0.5" long) awl-shaped leaves. It blooms with showy red flowers. 

In the wild, it can reach up to 13' tall at maturity!