Desert-Thorn

Near Quitobaquito Springs in Organ Pipe Cactus National Monument I saw a very striking shrub with ripe orange/red fruit. 

The thorn-berry, with red fruit just visible.

Closer view.

I've not been able to pin it down, but I think it may be what is known as the Arizona desert-thorn (lysium exsertum), found only in small portions of Arizona, mostly the south, and into northern Mexico. It has green tear-drop shaped leaves and lavender flowers. The flowers, of course, turn into the fruit and the one I saw was in the fruit stage with the flowers all gone. 

Closer view of the fruit.