This is the nominate variety of Texas Paloverde, formerly placed in the genus Cercidium. It is a shrubby form of the larger, tree-form P. texana var. macra (formerly Cercidium macrum). It has a limited distribution in desert scrub in Southwestern Texas. (Note that there is only one pair of pinnae on the single leaf that I photographed--a distinguishing character.)
http://plants.usda.gov/core/profile?symbol=PATET2
http://bonap.net/MapGallery/County/Parkinsonia%20texana.png