This is a Smoke Tree (Dalea Spinosa).  They live in the washes and canyons of our local desert and, I assume, other dry, arid places in the Sonoran Desert region.  I found this one in Anza-Borrego's Canyon sin Nombre (canyon with no name).  I have taken hundreds of pictures of smoke trees during desert hikes but rarely have any that I like enough to do the post processing.  They look much more lively and interesting in the wild than they do as a two dimensional photograph.  The tree's tiny leaves are a greenish-gray and golden brown which gives it a smokey look.  A look that I couldn't get to work in a color photograph, thus the B&W.  It helps that we had rain clouds overhead that day which gives the image a dramatic backdrop at the expense of a drenching later in the hike. What I really liked about this particular tree is the dead branches that reach out from its center.  They were bleached white, creating a nice focal point.  

Smoke Tree